“Everyone builds on other men's failures. There is nothing really original in science. What each man contributes to the sum of knowledge is what counts.”

Variant: Education is the sum of what students teach each other between lectures and seminars.

§ I
1910s, At the Feet of the Master (1911)
Context: In all the world there are only two kinds of people — those who know, and those who do not know; and this knowledge is the thing which matters. What religion a man holds, to what race he belongs — these things are not important; the really important thing is this knowledge — the knowledge of God's plan for men. For God has a plan, and that plan is evolution. When once a man has seen that and really knows it, he cannot help working for it and making himself one with it, because it is so glorious, so beautiful. So, because he knows, he is on God's side, standing for good and resisting evil, working for evolution and not for selfishness.
If he is on God's side he is one of us, and it does not matter in the least whether he calls himself a Hindu or a Buddhist, a Christian or a Muhammadan, whether he is an Indian or an Englishman, a Chinaman or a Russian. Those who are on His side know why they are here and what they should do, and they are trying to do it; all the others do not yet know what they should do, and so they often act foolishly, and try to invent ways for themselves which they think will be pleasant for themselves, not understanding that all are one, and that therefore only what the One wills can ever be really pleasant for any one. They are following the unreal instead of the real. Until they learn to distinguish between these two, they have not ranged themselves on God's side, and so this discrimination is the first step.
But even when the choice is made, you must still remember that of the real and the unreal there are many varieties; and discrimination must still be made between the right and the wrong, the important and the unimportant, the useful and the useless, the true and the false, the selfish and the unselfish.

Source: A Rule Against Murder

Imagination, Understanding, and the Virtue of Liberality, ch. 4

Lecture at Yale University, "Chemical Achievement and Hope for the Future." (October 1947) Published in Science in Progress. Sixth Series. Ed. George A. Baitsell. 100-21, (1949).
1940s-1960s
Context: Science cannot be stopped. Man will gather knowledge no matter what the consequences – and we cannot predict what they will be. Science will go on — whether we are pessimistic, or are optimistic, as I am. I know that great, interesting, and valuable discoveries can be made and will be made… But I know also that still more interesting discoveries will be made that I have not the imagination to describe — and I am awaiting them, full of curiosity and enthusiasm.

Jämmerlich ist freilich jene praktische Philosophie der Franzosen und Engländer, von denen man meint, sie wüßten so gut, was der Mensch sei, unerachtet sie nicht darüber spekulierten, was er sein solle.
Cited in Lucinde and the Fragments, P. Firchow, trans. (1991), "Athenaeum Fragments" (1798), § 355.

The Birthgrave (1975)
Source: Book Two, Part V “Tower-Eshkorek”, Chapter 3 (p. 303)

version in original Dutch (citaat uit een brief van Maria Bilders-van Bosse, in het Nederlands:) Wat is het leven moeilijk en omslachtig, en wat heeft men een toer om zijne eigen gedachten, gevoelens regt naar waarheid te doorgronden – te zuiveren en achter elkaar te plaatsen.
Quote from her letter to sister Anna, The Hague, 12 Jan. 1879; as cited in Marie Bilders-van Bosse 1837-1900 – Een Leven voor Kunst en Vriendschap, Ingelies Vermeulen & Ton Pelkmans; Kontrast ( ISBN 978-90-78215-54-7), 2008, p. 21