When we insist, as all the wisest child psychologists do now, that every child is like a small scientist, we don't mean that she has esoteric knowledge of a broad range of subjects, or talks to angels, or makes lead into gold. We mean that she makes a theory about how her blocks are going to fall down and then tests it by knocking them over. And her range of knowledge in that way grows by leaps and bounds. Science is really just that child's groping, with wings on - no, not with wings on, rather up on stilts, awkward-looking earthbound instruments, that get you high enough to see the world. There's supposed to be a sign up on the Tower Of Pisa: "Please don't throw things from this tower". That sign is the best memorial that Galileo could ever have. Of course, I'm not sure that it's actually there. I'll have to go and look.