Locke thinks we don't understand, and probably never will understand how objects in the material world gives rise to ideas.

Comment:

Two polar possible responses:

1. Well, there are still a lot of puzzles in this area, but we are getting there. (Dennett)

2. Yes, it is a mystery, we don't have a clue about even the shape of an explanation of how physical events can 'give rise to' mental ones. (Everybody else - but my own money is on Dennett)