“On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammeled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided. But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains.”

Source: Lacon (1820) Vol. I; CCCCXXVII (7th Edition, published by Longman, Hurst, Rees, Orme, and Brown, in 1821)

Source: The Yellow Book, 1974, p.65

The Unclassed (1884), ch. 1: School

Vol. I; CCCCXXVII (7th Edition, published by Longman, Hurst, Rees, Orme, and Brown, in 1821)
Lacon
Context: To know the pains of power, we must go to those who have it; to know its pleasures, we must go to those who are seeking it; the pains of power are real, its pleasures imaginary.

Book IV, sec. 7
Tetrabiblos

Source: "Unsafe at Any Speed or: Safe, Sane and Consensual, My Fanny", p. 14

Sec. 13
The Gay Science (1882)

Variant translations:
Zeus has led us on to know,
the Helmsman lays it down as law
that we must suffer, suffer into truth.
We cannot sleep, and drop by drop at the heart
the pain of pain remembered comes again,
and we resist, but ripeness comes as well.
From the gods enthroned on the awesome rowing-bench
there comes a violent love.
Robert Fagles, The Oresteia (1975)
God, whose law it is
that he who learns must suffer.
And even in our sleep, pain that cannot forget
falls drop by drop upon the heart,
and in our own despite, against our will,
comes wisdom to us by the awful grace of God.
Edith Hamilton, The Greek Way (1930), pp. 61 and 194 ( Google Books https://books.google.com/books?id=D3QwvF3GWOkC&lpg=PA61&ots=BacvHvGm6e&dq=%22And%20in%20our%20own%20despite%2C%20against%20our%20will%2C%20Comes%20wisdom%22%20-kennedy&pg=PA194#v=onepage&q=%22our%20own%20despite%22&f=false)
Robert F. Kennedy quoted these lines in his speech announcing the assassination of Martin Luther King, Jr. on 4 April 1968. His version http://www.americanrhetoric.com/speeches/rfkonmlkdeath.html:
Even in our sleep, pain which cannot forget
falls drop by drop upon the heart
until, in our own despair, against our will,
comes wisdom through the awful grace of God.
Variant translations of πάθει μάθος:
By suffering comes wisdom.
The reward of suffering is experience.
Wisdom comes alone through suffering.
Source: Oresteia (458 BC), Agamemnon, lines 176–183, as translated by Ian Johnston ( Google Books https://books.google.com/books?id=qz1HpBZ1fTwC&lpg=PA13&ots=C7aohrZRF1&dq=Drips%20in%20our%20hearts%20as%20we%20try%20to%20sleep%2C&pg=PA13#v=onepage&q=Drips%20in%20our%20hearts%20as%20we%20try%20to%20sleep,&f=false)