Letters 124.16

The dumb animal comprehends the present world about him through his senses alone. He remembers the past only by meeting with something which reminds his senses; a horse, for example, remembers the right road only when he is placed at the starting-point. In his stall, however, he has no memory of the road, no matter how often he may have stepped along it. The third state—the future—does not come within the ken of dumb beasts.

Seneca, Letters to Lucilius 124.16, translated by Richard Mott Gummere