That one is a quote from Ken Thompson, the inventor of (among much else), Unix and UTF-8. It is quoted in _Programming Pearls_, though -- I think, in the sequel rather than the original.
As noted, a quotation from Ken Thompson. It appears in the chapter "Bumper Sticker Computer Science" in _More Programming Pearls" along with many other fine aphorisms.
This is one of my favorite programming quotes. I haven't seen it used much over the years.