 Different schools of classical philosophy have very different understandings of “analogy,” upamāna, and, unlike with perception, inference, and testimony, cross-school controversies seem often at cross-purposes. For example, Mīmāṃsakas, worried about the criteria for substitutes for materials enjoined to carry out rituals, talk about similarities as objective, whereas Naiyāyikas are concerned principally with word meanings, although Vātsyāyana (1997: 170–1) does show the usefulness of analogy to indicate something new, a medicinal plant, for instance, similar to one with which an interlocutor is familiar. Gaṅgeśa sees the working of analogy to result solely in learning the meaning of words. Nevertheless, appreciation of similarity, which he sees as a supervenient property, is, he says, crucial in the operation of the knowledge source. The Jewel’s chapter on analogy is quite short and lacks subsections, hardly a “chapter” in comparison with the other three.