“Good deeds remain good, no matter whether we know how the world was made or not. Vile deeds are vile, no matter whether we know or do not know what, after death, will be the fate of the doer. We know, at least, what his fate is now, namely, to be wedded to the vileness.
The question for anyone to decide, who hesitates between good and evil, is whether he aspires to be a full-weight man, or merely the fragment, nay, the counterfeit of a man. Only he who ceaselessly aims at moral completeness is, in the true sense, a human being.”

Source: The Causes of Evolution (1932), Ch. V What is Fitness?, pp. 158-159.
Context: I have given my reasons for thinking that we can probably explain evolution in terms of the capacity for variation of individual organisms, and the selection exercised on them by their environment....
The most obvious alternative to this view is to hold that evolution has throughout been guided by divine power. There are two objections to this hypothesis. Most lines of descent end in extinction, and commonly the end is reached by a number of different lines evolving in parallel. This does not suggest the work of an intelligent designer, still less of an all mighty one. But the moral objection is perhaps more serious. A very large number of originally free-living Crustacea, worms, and so on, have evolved into parasites. In doing so they have lost, to a greater or less extent, their legs, eyes, and brains, and have become in many cases the course of considerable and prolonged pain to other animals and to man. If we are going to take an ethical point of view at all (and we must do so when discussing theological questions), we are, I think, bound to place this loss of faculties coupled with increased infliction of suffering in the same class as moral breakdown in a human being, which can often be traced to genetical causes. To put the matter in a more concrete way, Blake expressed some doubt as to whether God had made the tiger. But the tiger is in many ways an admirable animal. We have now to ask whether God made the tapeworm. And it is questionable whether an affirmative answer fits in either with what we know about the process of evolution or what many of us believe about the moral perfection of God.

Source: Under the Volcano (1947), Ch. VII (*p. 201)

Source: Drenai series, Legend, Pt 1: Against the Horde, Ch. 23

Source: Fiction, The Book of the New Sun (1980–1983), The Urth of the New Sun (1987), Chapter 33, "Aboard the Alcyone" (p. 237)

Source: The Idea of History (1946), p. 10

As quoted in 3:AM magazine (1994) http://www.3ammagazine.com/musicarchives/2004/nov/interview_paul_simonon.html

Source: Practical Pictorial Photography, 1898, The photographic print, p. 36

Brekkukotsannáll (The Fish Can Sing) (1957)