It’s lurking on your bookshelf. Probably on the bottom shelf, because it’s heavy. A very expensive hardcover that you once carried around during the day and spent time with late at night. It’s the college textbook. Maybe even the high school textbook. We know you still have it; everyone does.
These are tough to get rid of. For one thing, they cost a lot of money. They are probably the most expensive books you own. For another thing, they are full of valuable information that you needed to know at one time. Maybe, if your memory is better than most, you still know it. Maybe (I find this much less likely) it was actually useful in your chosen career and you still use that information. Maybe (least likely of all) you truly enjoyed that subject and like to pick the book up and reminisce.
The sad fact is, the only way to recover some of the money you spent is to sell it back to the university bookstore (if you are so fortunate as to have such a program,) or to a student taking that course the following semester. Texts have expiry dates shorter than the carton of cream in your fridge. If it has been sitting more that a year, no one wants it. Nope, not even the garage sale fans or the second-hand bookstore.
And if you haven’t opened it during that year, you aren’t going to again. You either know the info because you use it all the time (so you don’t open the book,) or you don’t need to know it any more (ditto.)
In the unlikely event that life hands you a pop quiz (What is the formula to find the area of a circle?!) you can find it on the internet (which you obviously know how to use, because you are reading this.)
So get up, grab that book, thank it for the education, and put it in the recycling. If it is a hardcover, you may have to put the cover in the trash and recycle the innards. Your bookshelf- and your life- will be a little lighter.