hardly overestimate the extent of his reading. Among these books there was no lack of older as well as contemporary works treating of natural history. All these books were already in print at that time, and it so happens that Milan was the principal place of the young art of book printing in Italy.
When we proceed further we come upon a communication which may raise to a certainty the probability that Leonardo knew the vulture fable. The erudite editor and commentator of Horapollo remarked in connection with the text (p. 172) cited before: Caeterum hanc fabulam de vulturibus ciipide amplexi sunt Patres Ecclesiastici, ut ita argumento ex rerum natura petito refutarent eos, qui Virginis partum negabant; itaque apud omnes fere hujus ret mentio occurit.
Hence the fable of the monosexuality and the conception of the vulture by no means remained as an indifferent anecdote as in the case of the analogous fable of the scarebæus beetles; that church fathers mastered it in order to have it ready as an argument from natural history against those who doubted the sacred history.
