Authors:

When I say that life is like an onion, I mean this: if you don't do anything with it, it goes rotten. So far, that's no different from other vegetables. But when an onion goes bad, it can either do it from the inside, or the outside. So sometimes you see one that looks good, but the core is rotten. Other times, you can see a bad spot on it, but if you cut that out, the rest is fine. Tastes sharp, but that's what you paid for, isn't it?

Steven Brust (1999). “The Book of Jhereg”, p.242, Penguin
When I say that life is like an onion, I mean this: if you don't do anything with it, it goes rotten. So far, that's no different from other vegetables. But when an onion goes bad, it can either do it from the inside,