You are in good company: “When I have a little money, I buy books; and if I have any left, I buy food and clothes.” - Erasmus

Maybe he meant professional help from a librarian.

@AzorAhai--hehim But possibly more than the number of math books that the library holds.

@mkennedy Still exceedingly unlikely, unless this is a very small university or the professor meant the departmental library or something.

As someone with a similar "addiction", I'd strongly recommend a policy of redirecting the impulse of buying a new book towards opening an existing, unread book on the same topic first. It doesn't really keep the stacks from growing, but at least it greatly increases the number of books where you've read the first few chapters. If the introductions are well written, it also gives you a broad knowledge about the general ideas in a lot of topics, which at least to me has been incredibly useful from time to time.

How he said it is more important than what he actually said, something which you did not specify.

I'd just like to offer my sympathies. People can be unnecessarily rude to people who have different habits than themselves. I had a passingly similar interaction a few weeks ago, and yes it can be surprising and hurtful.

Your enthusiasm and your library are wonderful and anyone making fun of it is simply jealous that they didn’t do the same thing when they were younger.

Also, have you checked out YouTube? From the awesome “3 blue 1 brown” and so on, to graduate level lectures by Fields medallists like Richard Borcherds (mathematics) and Edward Witten (physics). I make no apology whatsoever for feeding your admirable addiction.

That you have more math books than the university library seems more of the university library's problem than yours. If paying for the books you buy doesn't pose a financial problem for you, then it's your business. Everyone needs a hobby, and collecting math books is less problematic than many.

Hint - mathematics professors are sometimes deficient in social skills.

It would be useful to know how many of the 1100 maths books you have read, and which ones you have "sorted through" to know if they are worth reading, and "how you select the books that you buy", based on reviews or feeling or title? Essential for the topic of book wisdom, because, I never read a single maths books, but I program digital signal processing which is quite advanced mathematics, resolving puzzles leads you to maths litterature like stepping stones.

I've sworn to myself I will absolutely seek professional help next time when I decide to move. There's nothing worse than carrying an endless stream of book boxes. And you'll get occasionally visitors who will ask if you actually have read all of those books. You might want to prepare an interesting reply in advance ;) Other than that, you'll be fine. And you are not alone.

You're fine. I have at least a couple hundred physical math books. I've only read parts of most of them, but you never know when some section of a book is going to greatly clarify something.

Note that it is theoretically possible for the professor to be right about the remedy, and wrong about the diagnosis.

Is there any chance that the professor was simply joking? Some mathematicians have deadpan humor.

It's a joke. Maybe semi-serious. Only you can judge if you have a problem. (The standard could be whether you spend unreasonably/compulsively/beyond your means on books you will don't open or read.) Nothing to be offended by.

If anything is worth collecting in this world, it's books.

If this comment really makes you think so much that you ask a question in this forum (instead of just dismissing the comment as stupid) you either have to toughen up or lose the view that professors are gods who are always good and right and moral. Otherwise, you are likely to get crashed somewhen in life by other people.

You like books, you don't need professional help, they do for such a comment! That professor may like sports, they might spend many hours per week watching a football game, in this same time, you could read another book and they could quickly add up! Do want you like, follow your own dreams!

I did think "you need professional help" could have been a dig at her math ability, not her collecting. Something along the lines of "well, a real mathematician doesn't need anything beyond Euclid". In any case, probably a cover for sexism.

Why do you care what the professor things about your book collection?

@Auspex: Why do you assume sexism? Also, who is "her"? Do you assume OP is a woman?