  The Wax Tablet passage offers us a more explicit account of the nature of thought, and its relationship with perception. The story now on offer says explicitly that perception relates to thought roughly as Humean “impressions” relate to Humean “ideas” (191d; compare Hume, First Enquiry II). The objects of perception, as before, are a succession of constantly-changing immediate awarenesses.  The objects of thought, it is now added, are those objects of perception to which we have chosen to give a measure of stability by imprinting them on the wax tablets in our minds. (The image of memory as writing in the mind had currency in Greek thought well before Plato’s time: see e.g. Aeschylus, Eumenides 275.)