Great books are always contemporary. In contrast, the books we call "contemporary". because they are currently popular, last only for a year or two, or ten at the most. You probably cannot recall the names of many earlier best sellers and you probably would not be interested in reading them. But the great books are never outmoded by the movement of thought or the shifting winds of doctrine and opinion.
People regard the "classics" as the great has-beens, the great books of other times. "Our times are different," they say. On the contrary, the great books are not dusty remains for scholars to investigate, they are, rather, the most potent civilizing forces in the world today.
Great books are the most readable. They will not let you down if you try to read them well. They have more ideas per page than most books have in their entirety. That is why you can read a great book over and over again and never exhaust its contents.