On the Shortness of Life, Section 10

Seneca — The Senator

Life has three parts: what has already happened, what is happening now, and what will happen. Of these three, the present moment is brief. The future is uncertain. But the past is solid and real — Fortune can't touch it anymore, and no one else can control it. This is exactly what busy people lose. They have no time to look back at their past. And even if they did have time, they wouldn't enjoy it. They regret too much. So they refuse to think about the time they've wasted. They hate reviewing their past choices because the mistakes become obvious when you look twice — even though those same choices seemed so appealing when immediate pleasure was calling the shots.

Seneca — The Senator Original

Life is divided into three parts: that which has been, that which is, and that which is to come: of these three stages, that which we are passing through is brief, that which we are about to pass is uncertain, and that which we have passed is certain: this it is over which Fortune has lost her rights, and which can fall into no other man's power: and this is what busy men lose: for they have no leisure to look back upon the past, and even if they had, they take no pleasure in remembering what they regret: they are, therefore, unwilling to turn their minds to the contemplation of ill-spent time, and they shrink from reviewing a course of action whose faults become glaringly apparent when handled a second time, although they were snatched at when we were under the spell of immediate gratification.