The last chapter of Scepticism and Animal Faith by Santayana is a relief after the previous three which seemed for me to hover on the brink of making sense. This chapter is entitled Comparison with Other Criticisms of Knowledge and is an examination of the wrong turn into literary psychology taken by Descartes and Hume. It is called literary because it replicates the standard approach of an author who has privileged access to the mind of his characters. As an aside the 'show rather than tell' as a writer's maxim only follows the ontic. Maybe Dickens and Wittgenstein were right: 'the human body is the best picture of the human soul'. (Body includes all its motions)
Professor Edward Feser exhumes Hume as he forgot to write himself - he is fond of the eponymous pun.
Feser on Hume
From Scepticism and Animal Faith:
Hume seems to have, assumed that every perception perceived itself. He assumed further that these perceptions lay in time and formed certain sequences. Why a given perception belonged to one sequence rather than to another, and why all simultaneous perceptions were not in the same mind, he never considered ; the questions were unanswerable, so long as he ignored or denied the existence of bodies. He asserted also that these perceptions were repeated, and that the repetitions were always fainter than the originals—two groundless assertions, unless the transitive force of memory is admitted, and impressions are distinguished from ideas externally, by calling an intuition an impression when caused by a present object, visible to a third person, and calling it an idea when not so caused. Furthermore, he invoked an alleged habit of perceptions always to follow one another in the same order—something flatly contrary to fact ; but the notion was made plausible by confusion with the habits of the physical world, where similar events recur when the conditions are similar. In tuitions no doubt follow the same routine ; but the conditions for an intuition are not the previous intuitions, but the whole present state of the psyche and of the environment, something of which the previous intuitions were at best prophetic symptoms, symptoms often falsified by the event.