“It was, perhaps, one of those cases in which advice is good or bad only as the event decides.”

That which is seen and that which is not seen (Ce qu'on voit et ce qu'on ne voit pas, 1850), the Introduction.
Context: In the department of economy, an act, a habit, an institution, a law, gives birth not only to an effect, but to a series of effects. Of these effects, the first only is immediate; it manifests itself simultaneously with its cause — it is seen. The others unfold in succession — they are not seen: it is well for us, if they are foreseen. Between a good and a bad economist this constitutes the whole difference: the one takes account only of the visible effect; the other takes account of both the effects which are seen and those which it is necessary to foresee. Now this difference is enormous, for it almost always happens that when the immediate consequence is favourable, the ultimate consequences are fatal, and the converse. Hence it follows that the bad economist pursues a small present good, which will be followed by a great evil to come, while the true economist pursues a great good to come, at the risk of a small present evil.

Source: Liberty, Equality, Fraternity (1873-1874), Ch. 2

The Contemporary English Novelist, La Nouvelle Revue française (1 May 1927)

A Dreary Story or A Tedious Story (1889)

Right and wrong exist as conceptions of mind, because there are portions of the universe capable of happiness and misery. Erase sentiency from the universe and you erase the possibility of ethics. Every conscious portion of the universe, therefore, has ethical relations to every other conscious portion (man, woman, worm, Eskimo, oyster, ox), but not to inanimate portions (clod, cabbage, river, rose), because the ones are sentient and the others are not.
Source: Better-World Philosophy: A Sociological Synthesis (1899), The Social Problem, pp. 81–82

A Voice from the Attic (1960)

Source: A Tale of Time City (1987), pp. 78-79.