The idea that opposites are somehow alike may seem strange and paradoxical, but the fact is that in order to be opposed, two things do have to be at least on the same spectrum. Hot and cold are both temperatures, sweet and bitter are both flavors, and so on. We can apply this concept when we are trying to set up a contrast in a text by asking what kind of thing each term is, or what it applies to. We rule out anything that doesn't have the same scope as the other term in the contrast.