Just as the same chain fastens the prisoner and the soldier who guards him, so hope and fear, dissimilar as they are, keep step together; fear follows hope.  I am not surprised that they proceed in this way; each alike belongs to a mind that is in suspense, a mind that is fretted by looking forward to the future.  But the chief cause of both these ills is that we do not adapt ourselves to the present, but send out thoughts a long way ahead.

Seneca, Epistulae, V