“Divine Providence only gives man as much as he is prepared to receive; if his receptive capacity be small, he obtains little, and much if it be great.”

Book XLII: Ch. 18: A summary of the changes which have occurred around the globe in my lifetime
Mémoires d'outre-tombe (1848 – 1850)
Context: How small man is on this little atom where he dies! But how great his intelligence! He knows when the face of the stars must be masked in darkness, when the comets will return after thousands of years, he who lasts only an instant! A microscopic insect lost in a fold of the heavenly robe, the orbs cannot hide from him a single one of their movements in the depth of space. What destinies will those stars, new to us, light? Is their revelation bound up with some new phase of humanity? You will know, race to be born; I know not, and I am departing.

45 Antigonus I
Apophthegms of Kings and Great Commanders

Listen, Little Man! (1948)
Context: You are different from the really great man in only one thing: The great man, at one time, also was a very little man, but he developed one important ability: he learned to see where he was small in his thinking, and actions. Under the pressure of some task which was dear to him he learned better and better to sense the threat that comes from his smallness and pettiness. The great man, then, knows when and in what he is a little man.

Source: Changes

The New Idolatry (1905), p. 242

Hating
The Note-Books of Samuel Butler (1912), Part XIV - Higgledy-Piggledy

Of the True Greatness of Kingdoms and Estates
Essays (1625)

Book IV, Ch. 19 : Of Enthusiasm (Chapter added in the fourth edition).
Variant paraphrase, sometimes cited as a direct quote: One unerring mark of the love of truth is not entertaining any proposition with greater assurance than the proofs it is built upon will warrant.
As paraphrased in Peter's Quotations : Ideas for our Time (1979) by Laurence J. Peter, p. 500; also in The Demon-Haunted World : Science as a Candle in the Dark (1994) by Carl Sagan, p. 64
An Essay Concerning Human Understanding (1689)
Context: He that would seriously set upon the search of truth, ought in the first place to prepare his mind with a love of it. For he that loves it not, will not take much pains to get it; nor be much concerned when he misses it. There is nobody in the commonwealth of learning who does not profess himself a lover of truth: and there is not a rational creature that would not take it amiss to be thought otherwise of. And yet, for all this, one may truly say, that there are very few lovers of truth, for truth's sake, even amongst those who persuade themselves that they are so. How a man may know whether he be so in earnest, is worth inquiry: and I think there is one unerring mark of it, viz. The not entertaining any proposition with greater assurance than the proofs it is built upon will warrant. Whoever goes beyond this measure of assent, it is plain receives not the truth in the love of it; loves not truth for truth's sake, but for some other bye-end.