"There is appearance, what things seem to be superficially. And then there is their real nature. These sometimes pull apart, and this is why science, which is in the business of discovering the essential nature of things, can tell us surprising things, such as that hummingbirds, ostriches, and falcons, however different they appear, are all birds—but bats, which look like birds, are not. We rely on these discoveries in everyday life. When you go to a doctor with a rash, you'll be unsatisfied if you're told that it looks like sunburn; you want to know that it really is—and this is what procedures such as blood tests and biopsies are for." Paul Bloom