Q. Hello! When indexing a book that names the same person literally hundreds of times (it’s about this person’s philosophy), is passim correct in the index? Same Q about his works; some of the famous works are named or referenced dozens, if not hundreds of times.
A. Imagine yourself using this index to find something. What good is passim? A reader already knows that X is mentioned throughout the book. Professional indexers disagree whether it even makes sense to have an entry for the main subject of a book, but if you do, it must be broken up into many subentries and possibly sub-subentries, so readers can find what they’re after. (In fact, any index entry that consists of more than five or six page numbers should be further broken down into subentries.) Some indexers of biographies create an entry for the person’s name, but within it they list only passages that relate to the person’s life events (birth, marriage, death), which could not easily be listed elsewhere in the index. Some indexers also put under the person’s name “Works. See titles of individual works.” Your questions show that you would profit from learning more about indexing before you go further. I suggest you read the indexing chapter of CMOS.