汗牛充栋

（形容书籍之多） (of a multitude of books) so many as to make the ox carrying them perspire and to fill a house to the rafters -- an immense number of books;enough books to make the ox carrying them sweat or to fill a house to the rafters -- an immense number of books;enough to fill the roof and cause cows to perspire before the cart -- numerous;in plenty [abundance] ;