This glass, when made, was, by the workman's skill,
The sum of sixty minutes to fulfil.
Time, more nor less, by it will out be spun,
But just an hour, and then the glass is run.
Man's life we will compare unto this glass,
The number of his months he cannot pass;
But when he has accomplished his day,
He, like a vapour, vanisheth away.

John Bunyan

http://www.poemhunter.com/poem/upon-the-hour-glass/