Edward Fitzgerald

The moving finger writes and, having writ, Moves on; nor all your piety nor wit Shall lure it back to cancel half a line, Nor all your tears wash out a word of it. - from The Rubaiyat of Omar Khayam

A moment's halt - a momentary taste Of being from the well amid the waste - And lo - the phantom caravan has reached The nothing it set out from - oh, make haste!