Lesson

A man took me aside and showed me an exquisite flower growing from a hairline crack in a thick bed of poured concrete. "There's a lesson to be learned here," he said, "large slabs of concrete should be sectioned with asphalt expansion seams."
                -- Milkman Dan

(I plucked this quote from a Usenet newsgroup, which is a fairly common culling ground for me. However, my usual attempt to verify quotes through primary sources was stymied by the fact that it is not so easy to search online for graphical text.)