I can't remember the rest but it's said to be by Piet Hein (not sure of the spelling). The old memory is not what it was, but I think it was published in 'Motes & Beams' which I have been told is long out of print.

He also wrote:-

If, of thy worldly goods thou art bereft
and of thy slender store, two loaves alone to thee are left
sell one
and with the dole
buy hyacinths to feed thy soul