Where is the boundary between human and animal? The Eighteenth Century and in particular Diderot wonder about it and, giving an answer, they unveil the deepest meaning of the creative process of nature. The human, whose time passes in the quest for novelty, cannot forget that life itself acts in us: that repetitive life, that animal life, punctuated by birth and death, by heartbeat and rhythm of breathing. The greatest and - perhaps - the oldest enigma of animal life is that it is, first of all, simply «life». While, in the creation of the human, the animal reveals itself, in animal creativity one can already glimpse the human.