Aristotle's On the Generation of Animals is referred to in Latin as De Generatione animalium. As with many of Aristotle's writings, the exact date of authorship is unknown, but it was produced in the latter part of the fourth century B.C. This book is the second recorded work on embryology that is treated as a subject of philosophy, being preceded by contributions in the Hippocratic corpus by about a century. It was, however, the first work to provide a comprehensive theory of how generation works and an exhaustive explanation of how reproduction works in a variety of different animals. As such, De Generatione was the first scientific work on embryology. Its influence on embryologists, naturalists, and philosophers in later years was profound. Among these were Hieronymus Fabricius, William Harvey, St. Thomas Aquinas, and Charles Darwin.