Opera Hero

  • Version 1.0
  • published 17 March 2023

1. Introduction

Opera emerged on the threshold of the 16th and 17th centuries in Italy as part of a courtly festive culture harkening back to antiquity. The new genre quickly gained popularity in other countries over the course of several decades in the 17th century. Some courts adopted the Italian model, others adapted this model to national or local traditions. In France, the ballet de cour gave rise to an independent form of opera, the tragédie en musique, which was based on the structure and demands of classical drama and integrated dances and choirs into the dramaturgy.

Although opera remained closely associated with the idea of courtly representation until the 19th century, it became a genre that also addressed a broader public as early as the 17th century. This happened first in the opera houses of the wealthy commercial city of Venice, which attracted an affluent international audience, and later in free trading cities of the German Empire such as Hamburg and Leipzig. Finally, in the 19th century, a time of extensive bourgeoisification and urbanisation of culture, opera reached wide circles of bourgeois society, and those circles’ need for representation and identification increasingly affected the conception of music-theatrical works.

2. Opera’s heroic characters

The opera librettists found their material and thus also their heroic characters in various sources. Like literature, painting or sculpture, many operas of the 17th to the early 19th century also drew on ancient myths and histories. The stories of heroes such as Heracles, Odysseus, Achilles, Theseus or Jason, which were often adapted into opera material, come from Greek mythology (see ⟶Homeric Heroes), while the Roman mythological world includes Aeneas, Gaius Mucius Scaevola or Gnaeus Marcius Coriolanus. Another important source of material was ancient history, with figures such as Julius Caesar, the emperor Titus Flavius Vespasianus, the general Flavius Aetius, and above all Alexander the Great. Historical figures from later history also found their way onto the opera stage, such as the Goth leader Alaric II, the English King Richard the Lionheart, or the Aztec ruler Montezuma. An important source of material for the first operas were early modern chivalric epics such as Lodovico Ariosto’s Orlando Furioso (1516–1523) or Torquato Tasso’s La Gierusalemme Liberata (1574), from which ⟶heroic figures such as Rinaldo, Orlando or Ruggiero originated. Many of these characters were able maintain their presence on the operatic stage for an astonishingly long time. In Rossini’s Armida, the crusader Rinaldo was still fighting the powerful, titular sorceress in 1817, and Antonín Dvořák’s opera based on the same material did not even see its premiere until the beginning of the 20th century.

In the second half of the 18th century, during the gradual bourgeoisification of art and society, heroic figures from more recent literary sources were also added: figures such as Romeo, Hamlet and Othello from Shakespeare, or heroes from Voltaire’s tragedies such as Tancrède, Arsace (from Sémiramis) and Nérestan (from Zaïre). Around 1800, updated ancient materials became the subject of many operas. In the early 19th century, originals by contemporary authors were enthusiastically adapted for musical theatre, such as the dramas of Friedrich Schiller or the poetry of Walter Scott, which were embraced by Italian Romanticism. The dramas of Shakespeare and Schiller were of great fascination to Giuseppe Verdi. Verdi’s contemporary Richard Wagner, on the other hand, found his heroic figures such as Tannhäuser, Lohengrin, Tristan, Siegfried and Parsifal primarily in medieval literature and the various sources of Nordic mythology.

3. Markings of the heroic

3.1. Heroic attributes

Most of the heroes who take the stage in operas of the 17th and 18th centuries are warriors whose heroic status can be recognised by heroic attributes (armour, weapons, etc.) and/or is underlined by other characters’ dialog. At a time when the mythological or (pseudo-)historical personnel of an opera was familiar to most opera-goers, hints were usually enough to make the heroic rank of a Perseus or of an Alexander clear to the audience. Heroic action on the open stage, for example in the form of a battle, is occasionally part of the plot, but never its main subject. In all operas, on the other hand, the theme of ‘love’ is of great or even central importance. In Italian opera, the hero is usually an eroe amante, a loving hero, i.e. a heroic figure in the field of tension between Mars and Venus.

3.2. Heroes in the “theatre of voices”

Opera is a “theater of voices”1Hadlock, Heather: “Women Playing Men in Italian Opera, 1810-1835”. In: Bernstein, Jane (Ed.): Women’s Voices Across Musical Worlds. Boston 2004: Northeastern University Press, 285-307, 285. in which the vocal register and the position of a role in the hierarchy of an ensemble are an important marker of heroic rank. However, the “voice of the hero” has been subject to a powerful historical change.

The male leads of the first operas were entrusted to tenors, singers who practiced the art of recitar cantando, of singing speech, in a vocal register related to that in which they spoke even without music. Early operas were committed to the idea of being elevated drama in music, violating as little as possible the precepts of verisimilitude (“verosimiglianza”) that applied to spoken theatre. Perhaps the early operatic heroes were also tenors because some of the first opera composers themselves sang in this register, such as Jacopo Peri and Giulio Caccini, who both set Ottavio Rinuccini’s libretto for L’Euridice to music in 1600. Although Euridice is the titular character in this work, the focus is on her hopelessly in love husband Orpheus, the Thracian singer of Greek mythology who was able to impress hardened hearts and even inanimate nature with his singing. Claudio Monteverdi also found his way to opera through the myth of Orpheus. As with his immediate predecessors Peri and Caccini, the title role in his favola in musica, or opera, L’Orfeo (1607) features a tenor. In other operas of the early 17th century, the tenor is also assigned the leading male role, such as in Francesca Caccini’s La liberazione di Ruggiero dall’isola d’Alcina (Florence 1625), as well as in Domenico Mazzocchi’s La catena d’Adone (Rome 1626), or Michelangelo Rossi’s Erminia sul Giordano (Rome 1633).

3.3. Castrati

From the 1640s onward, male lead roles in Venetian opera were predominantly filled by castrati. The title role of Odysseus in Monteverdi’s Il ritorno d’Ulisse in patria (which premiered in 1641 at the Teatro Santi Giovanni e Paolo) is intended for a tenor, but Achille (Achilleus) in Francesco Sacrati’s La finta pazza (1641) and Nerone (Nero) in Monteverdi’s last opera L’incoronazione di Poppea (1642) are castrato roles. They mark the beginning of a casting tradition that was to remain typical of Venetian opera.

The title role in Francesco Cavalli’s Il Giasone (1649), one of the most successful operas of the 17th century, is also a castrato role and in many ways exemplary of the way heroes were portrayed in Venetian opera. As eroe amante, Giasone (Jason) moves fundamentally between heroic and erotic action, but he rarely gets to perform heroic deeds because his complicated relationships with various women keep him otherwise fully occupied. As a result, Ercole (Heracles) accuses Giasone of having a “troppo molle effeminato ingegno”, a mind made effeminate from dealing with women. The contrast between the two heroes finds a counterpart in the casting: Ercole is assigned to a bass, a vocal register that in baroque opera stood for wisdom and authority, while the love-addiction of the youthful Giasone found its appropriate contemporary expression in the sound of the castrato voice.2McClary, Susan: “Gender Ambiguities and Erotic Excess in Seventeenth-Century Venetian Opera”. In: Franko, Mark / Richards, Annette (Eds.): Acting on the Past. Historical Performance across the Disciplines. Hanover/London 2000: Wesleyan University Press, 177-200, especially 187-190.

Venetian opera, with its abundance of intersecting plot lines, variety of different types of characters, and colourful jumble of serious and comic scenes, was entertainment of the highest order for a patrician audience able to recognise its own social predominance and conflicts on the stage. In this context, heroes did not serve as role models for a single ruler, because that would have contradicted the Venetians’ republican self-image. Therefore, Venetian opera has an almost anti-heroic tendency, which can be found in Giasone and other pieces.

In the 1670s, critical voices began to rise against this type of musical theatre. This ultimately led to a fundamental reform of Italian opera in the early 18th century. Through the interaction of many arts, the model of Venetian opera was further developed into the epitome of feudal court culture. In a return to the classical rules of poetics, the plot was simplified, comic elements were banished, and a musical dramaturgy was established that clearly distinguished between recitative and aria, between discursive-action-bearing and contemplative-affective moments. In this newly designed setting, the heroic figures acquired a different profile. They remained eroi amanti, but the hero’s love affinity was now staged not as an expression of weakness but as a complementary counterpart to his heroic stance. In this reformed guise, the heroic figures portrayed by castrati functioned, on the one hand, as glorification of a ruler who was supposed to identify with these heroes, and, on the other hand, as a kind of specula principum (mirror for princes), instructing rulers theatrically in ideal heroic behaviour and virtues.

3.4. Female singers “en travesti”

Casting women in heroic roles – costumed as men – was an alternative to castrati. This casting option did not become established until the end of the 17th century, when the occupation of female singer had freed itself from its close ties to the courtly context, and the increasing spread of opera as an institution had given rise to the new profession of female opera singer. The “new” practice of cross-gender casting, already familiar from the tradition of drama, offered many female singers the opportunity to play a wide range of roles. Many female singers sang both female and male roles, and some specialised in portraying heroic characters.3Woyke, Saskia: “Zur so genannten gegengeschlechtlichen Besetzungspraxis. Nebst einer Besprechung von Kordula Knaus, Männer als Ammen – Frauen als Liebhaber. Cross-gender casting in der Oper 1600 bis 1800, Stuttgart 2011 und Marco Beghelli und Raffaele Talmelli, Ermafrodite armoniche. Il contralto nell’Ottocento, Varese 2011”. In: ACT – Zeitschrift für Musik & Performance 3 (2012). Online at: (accessed on 19.11.2019).

As can be seen from the surviving cast lists, the number of women appearing in male roles in opera seria decreased continuously starting in the middle of the 18th century.4Knaus, Kordula: Männer als Ammen – Frauen als Liebhaber. Cross-gender casting in der Oper 1600 bis 1800. Stuttgart 2011: Steiner, 83. Although there is evidence of female singers in leading roles shortly before the turn of the century, these cases can be understood partly as exceptions, and partly as the beginnings of a new casting practice. The reasons for the decline are manifold. The opera seria, as it had established itself in the 1720s under the influence of the poet Pietro Metastasio, reduced the number of acting (and singing) characters to a minimum: prima donna and primo uomo are at the top of the ensemble hierarchy as the first couple (“prima coppia”), followed by seconda donna and secondo uomo as the secondcouple (“seconda coppia”), and finally, “a tenor representing a king, and, in the last part, a person of his court.”5“[…] sicchè il primo uomo fosse il soprano corrispondente della prima donna, il secondo uomo il soprano corrispondente della seconda donna, il tenore qualche re, e l’ultima parte qualche persona della sua corte.” Mattei, Saverio: La filosofia della musica. Padua 2008: Editoriale Programma, 52. In addition, opera buffa was passing opera seria in popularity and importance. In the context of an increasing bourgeoisification of the audience, the subject matter of operas also changed: Heroic stories of mythology or history were no longer in demand in opera buffa, but rather material with contemporary relevance and a personnel that encompassed all strata of society. Castrati, the epitome of opera seria, appeared only very rarely in buffa operas. Many theatres performed works of both operatic genres, but the number of opere serie performed declined overall. There were apparently enough castrati available to largely meet the remaining demand for primi and secondi uomini, so there were fewer and fewer opportunities for women en travesti.

3.5. Hautes-contres and tenors

The French opera was characterised by an aesthetic strongly oriented toward spoken tragedy; thus, there was no place for the extraordinary virtuosity of castrati, who were only accepted in the realm of church music in France. Beginning with Jean-Baptiste Lully, the heroic parts in the tragédies en musique were sung by high tenors (hautes-contres). Outside of French opera in the 18th century, it was individual, outstanding singers whose impressive skills established the gradual return of the tenor to the forefront of operatic hero roles. For example, in 1724, Francesco Borosini persuaded George Frideric Handel to extensively revise the already composed opera Tamerlano and adapt the part of Bajazet, which Borosini was to embody.6Cf. LaRue, C. Steven: Handel and His Singers. The Creation of the Royal Academy Operas, 1720-1728. Oxford 1995: Clarendon. In the years that followed, Handel continued to compose for tenors who were desirous and capable of being more than marginal figures. Some of them, such as Annibale Pio Fabri or Giovanni Battista Pinacci, achieved significant careers on the stages of Europe.

The trend toward the greater importance of tenor roles, which was presaged by Handel and others, continued in the second half of the 18th century. In the bourgeois-influenced genres, the opera buffa or the German Singspiel, tenors were offered new opportunities to distinguish themselves. In Mozart’s early opera buffa La finta giardiniera, the role of Don Ramiro is still a castrato as a relic of a dying tradition, but in Mozart’s singspiels and operas of the Viennese period, beginning with The abduction from the Seraglio and continuing through Così fan tutte to The Magic Flute, the tenor plays an undisputed leading role in most works.

But around the turn of the 19th century, a profound change also took place in the field of opera seria. The heroic roles, which had been the domain of the singer-castrati for about a century and a half, were increasingly taken over by other singers. Alongside the castrati, the contralto musico established itself. This wasa type of female singer who sang the leading male roles in opera seria and was oriented around the model of the castrati in terms of position and timbre. In roles such as Tancredi or Arsace (in Rossini’s work Semiramide) and many others, they enjoyed great success until the 1830s.7Cf. Seedorf, Thomas: Heldensoprane. Die Stimmen der eroi in der italienischen Oper von Monteverdi bis Bellini (Figurationen des Heroischen 1). Göttingen 2015: Wallstein. In addition to the contralto musico, tenors such as Andrea Nozzari or Giovanni David took on heroic roles like Pirro or Oreste (in Rossini’s Ermione). These were singers who were able to take their voices to extreme heights by perfectly linking the falsetto register to their tenor chest voice, thus bringing themselves tonally close to the female alto voices and in turn emulating, at least in part, the tonal ideal of the castrati.

At the height of Rossini’s European fame, a younger generation of composers and singers began to gradually abandon the virtuoso bel canto of opera’s grand master in search of new dimensions of dramatic and vocal expression. In no other work is the change more evident than in Vincenzo Bellini’s melodrama Il pirata (1827), whose male lead, that of the titular pirate Gualtiero, was written for Giovanni Battista Rubini. With the soft sheen of his voice and enormous expansion into the highest registers (up to the high F in Bellini’s last opera, I puritani), Rubini was a mediator between the older and younger generations. Other tenors, however, sought paths that had not been taken before. Domenico Donzelli, for example, was famous for the great penetrating power of his dark voice, which was most effective in the romantic operas of Saverio Mercadante and Bellini.

3.6. Tenore di forza and Heldentenor

Donzelli was one of the pioneers of a new type of tenor, the tenore di forza, which did not replace the older type of tenore di grazia, but was on an equal footing with it.8Cf. Seedorf, Thomas: “Heldentenor und Tenore di forza”. In: Jacobshagen, Arnold (Ed.): Verdi und Wagner. Cultures of Opera. Cologne/Weimar/Vienna 2014: Böhlau, 295-305. The figurehead of a new style of tenor singing, however, was Gilbert-Louis Duprez, a French singer who initially attracted little attention in his home country and continued his training in Italy, with, among others, Donzelli. He is considered the first to sing the high C, the mythical tenor tone par excellence, with the “voix de poitrine,” or the chest voice, in a 1837 performance of Rossini’s Guillaume Tell. The effect Duprez’ singing achieved was spectacular and tempted many tenors to imitate him.

There arose, in the second half of the 19th century, a German counterpart to the Italian tenore di forza and the French fort ténor, and its origins are almost exclusively linked to the name and work of a single composer: The Heldentenor came into being because Richard Wagner composed works for it.9Cf. Seedorf, Thomas: “Vom Tenorhelden zum Heldentenor – Wagners Ideal eines neuen Sängertypus”. In: Altenburg, Detlef / Bayreuther, Rainer (Ed.): Bericht über den XIII. Internationalen Kongress der Gesellschaft für Musikforschung vom 16. bis 21. September 2004 am Institut für Musikwissenschaft Weimar-Jena. Vol. 1. Kassel 2012, 463-472. Wagner’s original tenor experience was his encounter with Joseph Tichatschek, a Bohemian singer engaged at the Dresden court opera who had been trained according to the principles of the Italian school. Tichatschek sang the extremely demanding role of Rienzi in Wagner’s opera of the same name so convincingly that his perfectly trained, untiring, and powerful voice became the model on which Wagner based the vocal and tonal conception of his later Heldentenor roles. As a performer, however, Tichatschek fell far short of Wagner’s demands. Wagner’s search for a tenor who could meet both the vocal and acting requirements of his works, which were avant-garde by the standards of the time, turned into a lifelong project. He saw his ideal realised in Ludwig Schnorr von Carolsfeld, the first Tristan, but the singer died a few weeks after the premiere of Tristan und Isolde. It was only after Wagner’s death that the Heldentenor was able to establish itself on the world’s stages as a genuinely German voice.

4. Heroes – antagonists – companions

It is not possible to speak about the heroes in the opera of the 18th century in the singular. Despite the tendency toward formalisation and schematisation, opera seria offered scope for the development of a wide variety of characters. The spectrum ranges from warlike heroes such as Giulio Cesare, whose military deeds occupy a prominent place in the plot, and the Indian king Poro, who is defeated in battle by Alessandro magno, to the suffering hero Admetus, who is saved by the love of his wife Alceste.

The dramaturgical structure of an opera seria also includes the tension between a hero and his antagonist. In the “theatre of voices” of the 17th and especially the 18th century, this can be a tenor, or more rarely a bass, but the hero and his opponent often belong to the same vocal register, where they encounter each other on the same level.10Covell, Roger: “Voice Register as an Index of Age and Status in Opera seria”. In: Collins, Michael / Kirk, Elise K. (Eds.): Opera and Vivaldi. Austin 1984: University of Texas Press, 193-210.

The so-called secondary heroes are characters of similar rank and heroic attitude to, and social environment of the hero. In most opere serie up to the early 19th century, the vocal register of the secondary characters indicate a solidarity or a social relationship to the hero. In Handel’s opera of the same name, the crusader Rinaldo is assisted by two other knights: Goffredo (i.e. Gottfried von Bouillon, the leader of the Christian army in the First Crusade) and his brother Eustazio. Because they all sing in the alto register, the three knights form a homogeneous community. In Handel’s Radamisto, on the other hand, there are two opposing characters who sing in the same register as the title character: the prince Tigrane, who is in love with Radamisto’s wife Zenobia, and Fraarte, brother and commander of the tyrant Tiridate, who wages war against Radamisto. Here, too, vocal register functions as a marker of social rank. The eroe amante stands out in this context not because of his vocal register, but because of the musical-dramaturgical weight that the librettist and composer give him: He sings the most arias and is most often present on stage.

5. References

6. Selected literature

  • Cusick, Suzanne G.: “On Musical Performance of Gender and Sex”. In: Barkin, Elaine / Hamessley, Lydia (Eds.): Audible Traces. Gender, Identity, and Music. Zürich/Los Angeles 1999: Carciofoli, 25-48.
  • Freeman, Daniel E.: “La guerriera amante. Representations of Amazons and Warriors Queens in Venetian Baroque Opera”. In: MQ 80 (1996), 431-460.
  • Gerhard, Anselm: “Rollenhierarchie und dramaturgische Hierarchien in der italienischen Oper des 18. Jahrhunderts”. In: Hortschansky, Klaus (Ed.): Opernheld und Opernheldin im 18. Jahrhundert. Hamburg/Eisenach 1991: Verlag der Musikalienhandlung Wagner, 35-55.
  • Hadlock, Heather: “On the Cusp between Past and Future. The Mezzo-Soprano Romeo of Bellini’s I Capuleti”. In: The Opera Quarterly 17.3 (2001), 399-422.
  • Hadlock, Heather: “Women Playing Men in Italian Opera, 1810–1835”. In: Bernstein, Jane A. (Ed.): Women’s voices across musical worlds. Boston 2004: Northeastern University Press, 285-307.
  • Heller, Wendy: “The Queen as King: Refashioning Semiramide for Seicento Venice”. In: Cambridge Opera Journal 5 (1993), 93-114.
  • Heller, Wendy: “Reforming Achilles: Gender, Opera seria and the Rhetoric of the Enlightended Hero”. In: Early Music 26 (1998), 562-581.
  • Heller, Wendy: “Varieties of Masculinity. Trajectories of the Castrato from the Seventeenth Century”. In: British Journal of Eighteenth-Century Studies 28 (2005), 307-321.
  • Hortschansky, Klaus: “Der tragische Held in der italienischen Oper am Ende des 18. Jahrhunderts”. In: Hortschansky, Klaus (Ed.): Opernheld und Opernheldin im 18. Jahrhundert. Hamburg/Eisenach 1991: Verlag der Musikalienhandlung Wagner, 233-252.
  • Jacobshagen, Arnold: “Tenor oder Musico? Rollenbesetzungen und Geschlechtsidentität in der Neapolitanischen Oper des frühen 19. Jahrhunderts”. In: Betzwieser, Thomas (Ed.): Bühnenklänge. Festschrift für Sieghart Döhring zum 65. Geburtstag. Munich 2005: Ricordi, 47-58.
  • Ketterer, Robert C.: “Roman Republicanism and Operatic Heroines in Napoleonic Italy: Tarchi’s La congiura pisoniana and Cimarosa’s Gli Orazi e i Curiazi”. In: Montemorra Marvin, Robert / Thomas, Downing A. (Eds.): Operatic Migrations. Transforming Works and Crossing Boundaries. Aldershot 2006: Routledge, 99-124.
  • Knaus, Kordula: Männer als Ammen – Frauen als Liebhaber. Cross-gender Casting in der Oper 1600–1800. Stuttgart 2011: Steiner.
  • Kost, Katharina: Das tragico fine auf venezianischen Opernbühnen des späten 18. Jahrhunderts, Diss. phil. Heidelberg 2004.
  • LaRue, C. Steven: Handel and His Singers. The Creation of the Royal Academy Operas, 1720–1728. Oxford 1995: Clarendon.
  • Leopold, Silke: “‘Not Sex but Pitch’. Kastraten als Liebhaber – einmal über der Gürtellinie betrachtet”. In: Linde, Hans-Martin / Rapp, Regula (Eds.): Provokation und Tradition. Erfahrungen mit der Alten Musik. Stuttgart/Weimar 2000: Metzler, 219-240.
  • Leopold, Silke: “Frauen in Männernkleidern oder: Versuch einer Antwort auf die scheinbar sinnlose Frage, warum Marzelline Leonore nicht erkennt”. In: Lühning, Helga / Steinbeck, Wolfram (Eds.): Von der Leonore zum Fidelio. Vorträge und Referate des Bonner Symposions 1997. Frankfurt a. M. 2000: Lang, 147-158.
  • McClary, Susan: “Soprano Masculinity”. In: Purvis, P. (Ed.): Masculinity in Opera. Gender, History, and New Musicology. New York/London 2013: Routledge, 33-50.
  • Seedorf, Thomas: “Ein neuer Held! – Ein neuer Held? Zur aktuellen Diskussion über ein Stimmfach”. In: wagner spectrum 8.1 (2012), 55-67.
  • Seedorf, Thomas: “Heldentenor und Tenore di forza”. In: Jacobshagen, Arnold (Ed.): Verdi und Wagner. Kulturen der Oper. Cologne/Weimar/Vienna 2014: Böhlau, 295-305.
  • Seedorf, Thomas: “Wagners ‘Gesangsheld’ – Ludwig Schnorr von Carolsfeld als Tristan”. In: Fornoff, Christine / Unseld, Melanie (Eds.): Wagner – Gender – Mythen. Würzburg 2015: Königshausen & Neumann, 213-229.
  • Seedorf, Thomas: “Der doppelte Radamisto. Zur Besetzung von Heldenpartien bei Händel”. In: Händel-Jahrbuch 62 (2016), 165-176.
  • Seedorf, Thomas: “Die neue Stimme des fremden Helden. Gaetano Fraschini als Zamoro in Giuseppe Verdis Alzira”. In: Korte, Barbara / Aurnhammer, Achim (Eds.): Fremde Helden auf europäischen Bühnen (1600–1900). Würzburg 2017: Ergon, 217-231.
  • Walter, Michael: “Gesang als höfische Rollen-Vernunft. Kastraten in der opera seria”. In: Historische Anthropologie. Kultur – Gesellschaft – Alltag 8 (2000), 208-235.
  • Wiesend, Reinhard: “Der Held als Rolle: Metastasios Alexander”. In: Hortschansky, Klaus (Ed.): Opernheld und Opernheldin im 18. Jahrhundert. Hamburg/Eisenach 1991: Verlag der Musikalienhandlung Wagner, 139-152; ital. edition: “La rappresentazione dell l’eroe come ruolo dramatico: L’Alessandro di Metastasio”. In: Opera & libretto II. Florence 1993, 67-83.


Thomas Seedorf: Opera Hero. In: Compendium heroicum, ed. by Ronald G. Asch, Achim Aurnhammer, Georg Feitscher, Anna Schreurs-Morét, and Ralf von den Hoff, published by Sonderforschungsbereich 948, University of Freiburg, Freiburg 2023-03-17. DOI: 10.6094/heroicum/ohe1.0.20230317