twelve from Galileo to Liceti (which would have been lost had Liceti not inserted them into his own published works). Works Liceti's varied publications demonstrate his range of interests, from genetics and reproduction to gems and animals. His prodigious output once caused mathematician Bonaventura Cavalieri to write to Galileo Galilei that Liceti “makes a book a week ('esso fa un libro in una settimana').” At the end of his 1653 work Hieroglyphica (1653), Liceti included a list of 75 compositions to that point: Published: 53 Philosophica: 9 Philosophico-Medica: 9 Physico-Mathematica: 7 Physico-Medico-Theologica: 12 Philologica: 16 Ready for the press: 19 Philologica: 2 Philosophico-Mathematico-Theologica: 8 Philosophica: 6 Medicinalia: 3 Started: 3 Philosophica: 1 Medica: 1 Theologica: 1 This article follows a different division. Natural Philosophy Liceti's philosophical works mainly deal with natural philosophy, which he preferred to call “physiology.” In De animarum rationalium immortalitate libri quatuor, Aristotelis opinionem diligenter explicantes, published in 1629, Liceti expounded the opinions of Aristotle regarding the immortality of the soul. In the 1645 work De pietate Aristotelis erga Deum et homines, he argues that Aristotle most likely achieved eternal salvation in the afterlife. Many of Liceti's works in this area are especially concerned with problems of generation and development. In 1602, he published De ortu animae humanae, which examines the way in which the three parts of the soul (vegetative, sensitive, and rational) come to be joined with the human fetus. In De perfecta constitutione hominis in utero liber unus, published in 1616, he further explored the topic of embryogenesis. In this work, he differed from Aristotle in arguing that, in addition to a male seed, there is also a female seed, which contributes the vegetative soul to a fetus. Furthermore, he argued that these seeds were composed of particles from all over the parents' bodies, some of which contain the shape of the embryo. Liceti then used this theory to explain the inheritance of acquired characteristics, genetic abnormalities and interspecies hybrids. Liceti's primary work in the field of generation, and his most famous, is De monstruorum causis, natura et differentiis, originally published in Padua in 1616 then reprinted in 1634 with lavish illustrations. Here, Liceti described and classified a variety of developmental abnormalities and, for the first time, classified these based on their morphology, not their cause. Liceti did, however, provide explanations for these abnormalities, including the narrowness of the uterus, problems with the placenta,