Paracelsus (c.1493–1541) is the most famous physician of the sixteenth century. He has been called the father of modern chemistry and is legendary for his treatment of syphilis. He left behind a significant body of work that includes ruminations about alchemy, health, healing, mineralogy, theology and nature. The republication of his writings during the twentieth century divided his work into medical and chemical tracts, and religious tracts. Cislo argues that to understand Paracelsus, modern scholars need to avoid dividing his oeuvre into modern categories of science and theology. By focusing on themes of conception and gestation, she explores how Paracelsus' theological and medical interests overlapped, intertwined and converged.
Cislo argues that Paracelsus developed an understanding of the body as composed of two distinct sexes, revolutionizing early modern conceptions of the female body as an inversion of or flawed approximation of the male body. He compared human bodies to what he considered divinely created bodies, namely those of Christ, Mary, Adam and Eve. Paracelsus related human birth to these biblical figures and his thoughts about holy bodies led him to delineate his understanding of the nature of human bodies and the spiritual quality of human life, namely the process of embodiment.

"'contains stimulating interpretations and has the merit of highlighting a number of original aspects in Paracelsus's theory of conception.'"