Of human knowledge as a whole and in every branch of it, by far the largest part exists nowhere but on paper, — I mean, in books, that paper memory of mankind.

[Von dem menschlichen Wissen überhaupt, in jeder Art, existirt der allergrößte Theil stets nur auf dem Papier, in den Büchern, diesem papiernen Gedächtniß der Menschheit.]

Arthur Schopenhauer (1788-1860) German philosopher

Parerga and Paralipomena, Vol. 2, ch. 21 “On Learning and the Learned [Über Gelehrsamkeit und Gelharte],” § 254 (1851) [tr. Saunders (1890)]
    (Source)

(Source (German)). Alternate translation:

Of human knowledge in general and in every branch thereof, by far the greatest part exists always only on paper, in books, this paper-memory of mankind.
[tr. Payne (1974)]