Classics are not classics because hoary with age — they are the steel balls which have worn down mountains but remained unchanged in the mill of time. – Martin H. Fischer (1879–1962)

That is a good book which is opened with expectation and closed with profit. – Amos Bronson Alcott

Books, not which afford us a cowering enjoyment, but in which each thought is of unusual daring; such as an idle man cannot read, and a timid one would not be entertained by, which even make us dangerous to existing institution — such call I good books. – Henry David Thoreau