2. Why can't the "configuration, number, motion, or size of corpuscles" cause our sensations?
3. If the existence of corporeal substances is a contradiction, then why doesn't the same thinking apply to incorporeal substances (spirits)?
4. Why can't we have an idea of spirit? How is having a "notion" of spirit different from having an idea of spirit?
5. What distinguishes ideas that depend on my will from ideas of sense? And how can ideas be arranged according to the laws of nature without being necessarily connected?
6. What is the difference between a "real" thing (e.g., fire) and an image of the thing? Why doesn't Berkeley's position imply that there is no difference between real things and mere ideas or illusions?
7. In what sense does Berkeley retain the concept of corporeal substance, and in what sense does he reject it? And why call things ideas?
8. Why isn't the perception of things at a distance from us proof that things exist outside our minds?
9. What does Berkeley mean by saying that visible ideas constitute a language whereby we are informed about sensations of touch we will shortly experience?
10. If the existence of things depends on their being perceived, then why does this not imply that things go out of existence when they are not being perceived? And what does this tell us about the supposed infinite divisibility of matter?
11. What does Berkeley mean by saying that qualities are in the mind "not by way of mode or attribute, but only by way of idea"? And why does this lead him to say of a die (i.e., one of the cubes of dice) that it is nothing other than its modes or accidents?
12. What does Berkeley mean by saying that "we ought to think with the learned, and speak with the vulgar"?
13. Why does Berkeley say that ideas normally associated in terms of cause and effect are better understood as sign and thing signified?