What does this line of poetry mean?

Question

Clay lies still, but blood's a rover;

Breath's a ware that will not keep.

Up, lad: when the journey's over

There'll be time enough to sleep.

From: Reveilléé by A. E. Houseman

Answer 1

Cool stuff.

Reveillee, is the traditional "wake up" tune played in the military, and this poem is about just that--answering the call.

It's vague, so we don't know if the guy's waking up to enter battle, or if it's just metaphorical for getting involved in life.

Clay is synonymous with death (it is said our bodies return to the clay from whence they were created), but blood moves (roves), as it does when we're alive.

Breath is a ware (a product or tool) that will not keep, meaning we don't have it (live) forever.

Sort of like, get going, get up and live, because there will be plenty of time to sleep when you're dead.