 If lekta serve here, as elsewhere, as the content of these states, then lekta will not correspond solely to rational representations. But how, one might reasonably ask, can the represenations in nonrational animals and very young humans, who are without concepts and incapable of articulate speech, have lekta corresponding to them? There is a widespread assumption in the secondary literature that whether a lekton corresponds to a representation depends upon which concepts (if any) an individual possesses. But the Stoics cannot accept this assumption. Quite the contrary. They believe that a lekton is involved in every causal interaction, whether animate or inanimate: one body causes a lekton to become true or hold of another body, where the lekton specifies the fully determinate effect of the agent on the patient (Stobaeus 1.138.14; Sextus Empiricus Adv. math. 9.211; Clement of Alexandria Stromata 8.9.3–4; this point is rightly emphasized by Frede 1994). But this analysis of causation immediately becomes pertinent once we acknowledge that the Stoics also hold a causal theory of representation: they define representations as the effect – literally, an “impression” (tupōsis) – that in the paradigmatic case the object of representation produces on the soul (which on their view is a body); and they expressly compare this to the impression a signet ring makes in wax (Diogenes Laertius VII 50; Aetius 4.12.1–4; Plutarch On Common Conceptions 1084f–1085a), and they appeal to sigillary language again when they define the “secure” representation they regard as the criterion of truth and foundation of knowledge (phantasia katalēptikē), which represents the object that produces it in such rich detail that it could be distinguished from anything else, no matter how similar (Cicero Acad. 2.77–78; Sextus Empiricus Adv. math. 7.248 ff.; Diogenes Laertius VII 46).