Fortunio Liceti (1577-1657), lecturer of medicine in Padua from 1645, friend of Galileo, versatile and curious about subjects ranging from medicine to astronomy, and from philosophy to archaeology, is the reference for teratology with his famous work De monstrorum caussis, natura, et differentiis, richly illustrated, held in the Library of Pharmaceutical and Pharmacological Sciences in its second edition of 1634 (digital copy).
Liceti declares himself a follower of Aristotle, but differs, in fact, in the theories on generating. He believed in the existence of a female seed in addition to the male seed, both of which made from residual blood coming from all parts of the body of which they retain traces. This theory, derived from Hippocrates, Democritus, and Galen, was used by Liceti to explain embryonic development, in particular for the transmission of hereditary characteristics, hybridity and the creation of monstrosities, an approach with great consequences up to the time of Darwin (Ongaro p. 93).
In De monstrorum caussis, natura et differentiis, the teratological classification was undertaken according to morphological criteria and the casuistry is large, so much so that "it marks a good part of congenital malformations known today" (Ongaro p. 94). Only natural causes are among those noted such as compression of the membranes of the uterus, anomalies of the placenta or the amniotic fluid, malnutrition, traumas or diseases of the foetus. There are moral observations as well, as the cause to be found in "Phantasia" or in the "animi passionibus", or in the "imaginatione" of the parents to the "malos Daemones".

The illustrations also express an aspect of curiosity and divertissement, that goes beyond the scientific aspect, as in the crossbreeding of animals (p. 20 e 22) or in the man with an elephant head (p. 191) or with wings, horns or hooves (p. 187), up to the truly baroque manifestations (p. 256, 258-259).