All of a sudden, they stumble upon Archemides with a canteen full of water! Archemides says "One of you can have this canteen and you'll live, but only if you walk half way to it, stop, walk half way to it, etc., etc.

The mathematic, in anquish, lays his head in his arm and start to cry. "It can't be done" he rages.

The engineer looks at the mathematician in disgust, shrugs his shoulders, walks half way, stops, walks half way, stop, etc., etc. Finally he stops next to it, leans over, picks up the canteen and drinks.

Archemides and the mathematician both are in shock. Archemides exclaims "but how did you do that -- it's impossible!"

Again, the engineer shrugs. "I got close enough for practical purposes!"