 One plausible answer is that Spinoza has in mind here something like clarity and distinctness (cf. e.g. E2p38c), and so is in broad agreement with Descartes’s “rule” that true ideas can appear to us as clear and distinct. Don Garrett has suggested that, in addition to clarity and distinctness, we should understand adequacy as the “logical consistency of the represented object” (2018: ch.6). On this reading, true ideas are self-evidently true insofar as we can clearly and distinctly perceive the logical consistency of what they represent. This proposal has the virtue of tying together Spinoza’s two characterizations of truth – the extrinsic and the intrinsic one – into one neat package: given Spinoza’s commitment to necessitarianism (E1p33, E1p35), any logically consistent idea will represent not just a possible object but a necessary and actual one; hence we can know from the logical consistency of an idea alone that it in fact corresponds to its object.