A quote
You are right in asking why; the saying certainly stands in need of a commentary. It is because the life of such persons is always incomplete. But a man cannot stand prepared for the approach of death if he has just begun to live. We must make it our aim already to have lived long enough. No one deems that he has done so, if he is just on the point of planning his life.
Seneca·Letter 23 — On the True Joy Which Comes from Philosophy (§10)·trans. Gummere