On Liberty by John Stuart Mill Chapter 2 Page 70

existence, not a few persons may be found, who have realized its fundamental principles in all the forms of thought, have weighed and considered them in all their important bearings, and have experienced the full effect on the character, which belief in that creed ought to produce in a mind thoroughly imbued with it.

But when it has come to be an hereditary creed, and to be received passively, not actively — when the mind is no longer compelled, in the same degree as at first, to exercise its vital powers on the questions which its belief presents to it, there is a progressive tendency to forget all of the belief except the formularies, or to give it a dull and torpid assent, as if accepting it on trust dispensed with the necessity of realizing it in consciousness, or testing it by personal experience; until it