“Pleasant it is, when over a great sea the winds trouble the waters, to gaze from shore upon another's great tribulation: not because any man's troubles are a delectable joy, but because to perceive from what ills you are free yourself is pleasant.”
Book II, lines 1–4 (tr. Rouse)
De Rerum Natura (On the Nature of Things)
Original
Suave mari magno turbantibus aequora ventis e terra magnum alterius spectare laborem; non quia vexari quemquamst jucunda voluptas, sed quibus ipse malis careas quia cernere suave est.
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Lucretius 45
Roman poet and philosopher -94–-55 BCRelated quotes

“At last a pleasant river's mouth he finds,
Free from rough clifts, safe from disturbing winds.”
Book V
Homer His Odysses Translated (1665)

Canto I, lines 22–24 (tr. Mandelbaum).
The Divine Comedy (c. 1308–1321), Inferno

Journal entry (2 March 1861), Ch. 5 : The Beginning of the War.
Lucy Larcom : Life, Letters, and Diary (1895)
Context: What does cause depression of spirits? Heavy head and heavy heart, and no sufficient reason for either, that I know of. I am out of doors every day, and have nothing unusual to trouble me; yet every interval of thought is clouded; there is no rebound, no rejoicing as it is my nature to rejoice, and as all things teach me to do. We are strange phenomena to ourselves, when we will stop to gaze at ourselves; but that I do not believe in; there are pleasanter subjects, and self is a mere speck on the great horizon of life.

“Never trouble another for what you can do yourself”

Preface.
A History of Science Vol.1 Ancient Science Through the Golden Age of Greece (1952)

Source: Terre des Hommes (1939), Ch. I : The Craft
Context: I had a vision of the face of destiny.
Old bureaucrat, my comrade, it is not you who are to blame. No one ever helped you to escape. You, like a termite, built your peace by blocking up with cement every chink and cranny through which the light might pierce. You rolled yourself up into a ball in your genteel security, in routine, in the stifling conventions of provincial life, raising a modest rampart against the winds and the tides and the stars. You have chosen not to be perturbed by great problems, having trouble enough to forget your own fate as man. You are not the dweller upon an errant planet and do not ask yourself questions to which there are no answers. You are a petty bourgeois of Toulouse. Nobody grasped you by the shoulder while there was still time. Now the clay of which you were shaped has dried and hardened, and naught in you will ever awaken the sleeping musician, the poet, the astronomer that possibly inhabited you in the beginning.
The squall has ceased to be a cause of my complaint. The magic of the craft has opened for me a world in which I shall confront, within two hours, the black dragons and the crowned crests of a coma of blue lightnings, and when night has fallen I, delivered, shall read my course in the stars.