Solo singing is associated with the expression of passions during the 17th century. Cantatas were sung by women as well as castrati, playing an ambivalent game on gender, eroticism, and passions. Contemporary testimonies of these performances juxtaposed with the medical theory of the humors shows that both are based on the idea of a perfect male body, a and womanish body of the castrato, and an even worse female body. Poems reflect the conventional tropes of the male gaze: the lover oscillates between hot and cold; he is consumed by the fire of passion and frozen by the unwavering cruelty of his beloved. While we rightly read such changes of temperature as standardized extravagances of poetics, they are also deeply rooted in Early Modern scientific theories of the body. Performance was one part of sophisticated entertainments along with improvisation of poetry, discourses on love, and games of eloquence.