Books have always a secret influence on the understanding

From Adventurer by Samuel Johnson

Books have always a secret influence on the understanding: we cannot at pleasure obliterate ideas; he that reads books of science, though without any fixed desire of improvement, will grow more knowing; he that entertains himself with moral or religious treatises will imperceptibly advance in goodness; the ideas which are often offered to the mind will at last find a lucky moment when it is disposed to receive them.

A long held sentiment awaiting confirmation.