Metaphor metaphor, saying one thing in terms of another—"the mind is a garden," "time is a river"—lets us carry meaning from a familiar place to a new one. We take something we know well and use it to understand something we know less well. The metaphor does not mean the two are the same. It means we can see the second in the light of the first. That is how we extend our thinking. First, we have an idea that is hard to say directly. Then we find something else that behaves in a similar way. We say "it is like…​" or we use the word for the second thing to name the first. "She has a sharp mind." Sharp belongs to knives; we borrow it for mind. The metaphor works when the listener sees the connection. It fails when they take it too literally or not literally enough. Metaphors can mislead. If we forget they are partial, we can start to believe the mind really is a garden and then wonder why we cannot water it. So using metaphor well means knowing where the comparison holds and where it breaks. When we pass knowledge on, we often pass it in metaphors. Keeping them alive and knowing their limits is part of continuity. What metaphor do you use to understand something difficult? Where does it break down?