Letters 5.9

Beasts avoid the dangers which they see, and when they have escaped them are free from care; but we men torment ourselves over that which is to come as well as over that which is past. Many of our blessings bring bane to us; for memory recalls the tortures of fear, while foresight anticipates them. The present alone can make no man wretched. Farewell.

Seneca, Letters to Lucilius 5.9, translated by Richard Mott Gummere