“Consider that nothing in human life is stable; for then you will not exult overmuch in prosperity, nor grieve overmuch in adversity.”
Verse 42.
To Demonicus
Context: Consider that nothing in human life is stable; for then you will not exult overmuch in prosperity, nor grieve overmuch in adversity. Rejoice over the good things which come to you, but grieve in moderation over the evils which befall you, and in either case do not expose your heart to others; for it were strange to hide away one's treasure in the house, and yet walk about laying bare one's feelings to the world.
Help us to complete the source, original and additional information
Isocrates 23
ancient greek rhetorician -436–-338 BCRelated quotes
“Prosperity makes friends, adversity tries them.”
Maxim 872
Sentences, The Moral Sayings of Publius Syrus, a Roman Slave

“Prosperity is the blessing of the Old Testament; adversity is the blessing of the New.”
Of Adversity
Essays (1625)

“It was a saying of his that education was an ornament in prosperity and a refuge in adversity.”
Aristotle, 9.
The Lives and Opinions of Eminent Philosophers (c. 200 A.D.), Book 5: The Peripatetics

(Often shortened to "can't stand prosperity" as an unknown quote).
1840s, Heroes and Hero-Worship (1840), The Hero as Man of Letters

“Learning is an ornament in prosperity, a refuge in adversity, and a provision in old age.”

“Remorse sleeps during a prosperous period but wakes up in adversity.”
Le remords s'endort durant un destin prospère et s'aigrit dans l'adversité.
Variant translations: Remorse sleeps during prosperity but awakes bitter consciousness during adversity.
Remorse goes to sleep during a prosperous period and wakes up in adversity.
Source: Confessions of Jean-Jacques Rousseau (1765-1770; published 1782), Books II-VI, II

“For friendship makes prosperity more shining and lessens adversity by dividing and sharing it.”
Nam et secundas res splendidiores facit amicitia et adversas partiens communicansque leviores.
Section 22
Laelius De Amicitia – Laelius On Friendship (44 BC)

As quoted in Bibliotheca Sacra and Theological Review by ? Vol. IV, No. 8 (1847) by Dallas Theological Seminary, p. 107

“In prosperity our friends know us; in adversity we know our friends.”