Letter 121 — On Instinct in Animals (§20)

“Furthermore, in order that you may not suppose this to be the result of chance, they do not shrink from certain other things which you would expect them to fear, nor do they ever forget vigilance and care in this regard; they all possess equally the faculty of avoiding what is destructive. Besides, their fear does not grow as their lives lengthen. Hence indeed it is evident that these animals have not reached such a condition through experience; it is because of an inborn desire for self-preservation. The teachings of experience are slow and irregular; but whatever Nature communicates belongs equally to everyone, and comes immediately.”