“…the power of analogy doesn’t come from noticing a mere similarity of parts […] It comes from noticing relations among the parts, even if the parts themselves are very different. […] For an analogy to be scientifically useful, though, the correspondences can’t apply to a part of one thing that merely resembles a part of the other. They have to apply to the relationship between the parts, and even better, the relationship between the relationships, and to the relationships between the relationships between the relationships.”