Letter 121 — On Instinct in Animals (§18)

“Nature brings up her own offspring and does not cast them away; and because the most assured security is that which is nearest, every man has been entrusted to his own self. Therefore, as I have remarked in the course of my previous correspondence, even young animals, on issuing from the mother’s womb or from the egg, know at once of their own accord what is harmful for them, and avoid death-dealing things. They even shrink when they notice the shadow of birds of prey which flit overhead. No animal, when it enters upon life, is free from the fear of death.”