“Strange fate for man! He must perish if he get that, which he must perish if he strive not after. If he strive not after it he is no better than the brutes, if he get it he is more miserable than the devils.”

IX, 28
Meditations (c. 121–180 AD), Book IX

Es irrt der Mensch, so lang er strebt.
Variant translation: Man will err while yet he strives.
Prologue in Heaven
Faust, Part 1 (1808)

"The Contest in America," Fraser’s Magazine (February 1862); later published in Dissertations and Discussions (1868), vol.1 p. 26
Context: War is an ugly thing, but not the ugliest of things: the decayed and degraded state of moral and patriotic feeling which thinks that nothing is worth a war, is much worse. When a people are used as mere human instruments for firing cannon or thrusting bayonets, in the service and for the selfish purposes of a master, such war degrades a people. A war to protect other human beings against tyrannical injustice; a war to give victory to their own ideas of right and good, and which is their own war, carried on for an honest purpose by their free choice, — is often the means of their regeneration. A man who has nothing which he is willing to fight for, nothing which he cares more about than he does about his personal safety, is a miserable creature who has no chance of being free, unless made and kept so by the exertions of better men than himself. As long as justice and injustice have not terminated their ever-renewing fight for ascendancy in the affairs of mankind, human beings must be willing, when need is, to do battle for the one against the other.

The Fantastic Imagination (1893)
Context: "But a man may then imagine in your work what he pleases, what you never meant!"
 Not what he pleases, but what he can. If he be not a true man, he will draw evil out of the best; we need not mind how he treats any work of art! If he be a true man, he will imagine true things: what matter whether I meant them or not? They are there none the less that I cannot claim putting them there! One difference between God's work and man's is, that, while God's work cannot mean more than he meant, man's must mean more than he meant. For in everything that God has made, there is layer upon layer of ascending significance; also he expresses the same thought in higher and higher kinds of that thought: it is God's things, his embodied thoughts, which alone a man has to use, modified and adapted to his own purposes, for the expression of his thoughts; therefore he cannot help his words and figures falling into such combinations in the mind of another as he had himself not foreseen, so many are the thoughts allied to every other thought, so many are the relations involved in every figure, so many the facts hinted in every symbol. A man may well himself discover truth in what he wrote; for he was dealing all the time with things that came from thoughts beyond his own.

Source: The Dance of Life http://www.gutenberg.net.au/ebooks03/0300671.txt (1923), Ch. 5

Variant: He that hath a beard is more than a youth, and he that hath no beard is less than a man. He that is more than a youth is not for me, and he that is less than a man, I am not for him.
Source: Much Ado About Nothing

Vol. III, John XV: 22–27, p. 123
Expository Thoughts on the Gospels: St. John (1865–1873)

As quoted in a eulogy for Darrow http://www.positiveatheism.org/hist/darrow1.htm by Emanuel Haldeman-Julius (1938)