Read the passage from Theodore Roosevelt: An Autobiography.I could not name any principle upon which the books have been gathered. Books are almost as individual as friends. There is no earthly use in laying down general laws about them. Some meet the needs of one person, and some of another; and each person should beware of the booklover's besetting sin, of what Mr. Edgar Allan Poe calls "the mad pride of intellectuality," taking the shape of arrogant pity for the man who does not like the same kind of books.Using the context clues, what is the meaning of the word "principle" as used in the sentence?