“Those who will not be counselled, cannot be helped. More souls are ruined by pride than by any other sin whatever.”

E 11
Variant translations: Nothing is more conducive to peace of mind than not having any opinion at all.
Nothing is more conducive to peace of mind than not having any opinions at all.
Nothing contributes more to a person's peace of mind than having no opinions at all.
Aphorisms (1765-1799), Notebook E (1775 - 1776)

Vol. 2, Ch. 24 "Oracular Philosophy and the Revolt against Reason"
The Open Society and Its Enemies (1945)
Context: ... the attempt to make heaven on earth invariably produces hell. It leads to intolerance. It leads to religious wars, and to the saving of souls through the inquisition. And it is, I believe, based on a complete misunderstanding of our moral duties. It is our duty to help those who need help; but it cannot be our duty to make others happy, since this does not depend on us, and since it would only too often mean intruding on the privacy of those towards whom we have such amiable intentions.

Source: Middlemarch

Le péché, c'est ce qui obscurcit l'âme.
La Symphonie Pastorale (1919)

Said to Malcolm Muggeridge, as quoted in Richard Ingrams (1996), Muggeridge: The Biography, p. 233

First Dialogue, Delmonce
Philosophy in the Bedroom (1795)

Light (1919), Ch. XVI - De Profundis Clamavi
Context: We cannot say out of what historical conjunctions the final tempests will issue, nor by what fancy names the interchangeable ideals imposed on men will be known in that moment. But the cause — that will perhaps everywhere be fear of the nations' real freedom. What we do know is that the tempests will come.
Armaments will increase every year amid dizzy enthusiasm. The relentless torture of precision seizes me. We do three years of military training; our children will do five, they will do ten. We pay two thousand million francs a year in preparation for war; we shall pay twenty, we shall pay fifty thousand millions. All that we have will be taken; it will be robbery, insolvency, bankruptcy. War kills wealth as it does men; it goes away in ruins and smoke, and one cannot fabricate gold any more than soldiers. We no longer know how to count; we no longer know anything. A billion — a million millions — the word appears to me printed on the emptiness of things. It sprang yesterday out of war, and I shrink in dismay from the new, incomprehensible word.
There will be nothing else on the earth but preparation for war. All living forces will be absorbed by it; it will monopolize all discovery, all science, all imagination.

Source: The Judges