In his book, which is a sort of summa of his philosophy, Ferraris outlines a general and comprehensive ontology. To distinguish the three major regions within which everything can be classified, Ferraris makes use of the concepts of space and time specifying its distance from Kant and referring instead to Leibniz; but, trying to develop his thinking on this point, some problems arise. The article also summarizes the position of Mauro Dorato, that unlike Ferraris built his interpretation of space and time in a profound confrontation with science.