Letters 121.13

Everyone of us understands that there is something which stirs his impulses, but he does not know what it is. He knows that he has a sense of striving, although he does not know what it is or its source. Thus even children and animals have a consciousness of their primary element, but it is not very clearly outlined or portrayed.

Seneca, Letters to Lucilius 121.13, translated by Richard Mott Gummere