 This definition has affinities with Dedekind cuts as, with "n" and "q" both positive, "np" stands to "mq" as stands to the rational number (dividing both terms by "nq").Definition 6 says that quantities that have the same ratio are "proportional" or "in proportion".Euclid uses the Greek ἀναλόγον (analogon), this has the same root as λόγος and is related to the English word "analog".