a pig in a poke ... an item you purchase without having seen; a disappointment
I'm a squanderer when it comes to foreign language textbooks. Almost fourteen years
were have been
devoted to my English study, and I took up another language about two years ago. My bookshelves replete with three foreign languages: English, Korean and Chinese. And I must admit that some of those books came to nothing. They are sitting there for months, sometimes for years, in
mint condition without being opened a page of its introduction... What a waste. I have to be careful not to buy a pig in a poke. My allowance is limited, and I'm not allowed to go on a buying spree! In fact, it's my fault some of my books have never seen the light of day. They are not "a pig in a poke" actually. At a fancy bookstore, I have a tendency to act like a pig...
They have sat there for months, sometimes years, in mint condition, without even being opened to their introductory pages.
添削してくださったネイティブの方が、a pig in a poke について教えてくれました。
"pig in the poke" refers to getting something you didn't expect. In the Middle Ages, cats and dogs sealed in a bag (poke) were sometimes sold as suckling pig to unwary buyers. "Bring coals to Newcastle" might work well here.