“Man is not the creature of circumstances, circumstances are the creatures of men. We are free agents, and man is more powerful than matter.”

The Life and Works of Goethe (1855; repr. Boston: Ticknor and Fields, 1856) vol. 1, p. 30, often misattributed to Thomas Carlyle.
Context: Instead, therefore, of saying that Man is the creature of Circumstance, it would be nearer the mark to say that Man is the architect of Circumstance. It is Character which builds an existence out of Circumstance. Our strength is measured by our plastic power. From the same materials one man builds palaces, another hovels, one warehouses, another villas.

Guesses at Truth (1827)

Source: Bards of the Bible, 1850, Chapter 1

Source: Uncle Tom's Cabin (1852), Ch. 29 The Unprotected
Context: We hear often of the distress of the negro servants, on the loss of a kind master; and with good reason, for no creature on God's earth is left more utterly unprotected and desolate than the slave in these circumstances.
The child who has lost a father has still the protection of friends, and of the law; he is something, and can do something, — has acknowledged rights and position; the slave has none. The law regards him, in every respect, as devoid of rights as a bale of merchandise. The only possible acknowledgment of any of the longings and wants of a human and immortal creature, which are given to him, comes to him through the sovereign and irresponsible will of his master; and when that master is stricken down, nothing remains.
The number of those men who know how to use wholly irresponsible power humanely and generously is small. Everybody knows this, and the slave knows it best of all; so that he feels that there are ten chances of his finding an abusive and tyrannical master, to one of his finding a considerate and kind one. Therefore is it that the wail over a kind master is loud and long, as well it may be.

Draft for a Statement of Human Obligation (1943)
Context: Anyone whose attention and love are really directed towards the reality outside the world recognizes at the same time that he is bound, both in public and private life, by the single and permanent obligation to remedy, according to his responsibilities and to the extent of his power, all the privations of soul and body which are liable to destroy or damage the earthly life of any human being whatsoever.
This obligation cannot legitimately be held to be limited by the insufficiency of power or the nature of the responsibilities until everything possible has been done to explain the necessity of the limitation to those who will suffer by it; the explanation must be completely truthful and must be such as to make it possible for them to acknowledge the necessity.
No combination of circumstances ever cancels this obligation. If there are circumstances which seem to cancel it as regards a certain man or category of men, they impose it in fact all the more imperatively.
The thought of this obligation is present to all men, but in very different forms and in very varying degrees of clarity. Some men are more and some are less inclined to accept — or to refuse — it as their rule of conduct.

Source: Silence

XVII. 446–447 (tr. R. Lattimore); Zeus.
Robert Fagles's translation:
: There is nothing alive more agonized than man
of all that breathe and crawl across the earth.
Iliad (c. 750 BC)