"Humanity in general possesses an experience of ['the values of purity'] as of other moral values . . . and sexual immorality rests, not on a literal absence of that experience but (apart from the 'weakness of the flesh' proper which is apt to stifle it) on the intellectual counter-pressure of hedonistic ideologies. Now such a 'repression' of the moral sense by adverse ideology is particularly likely to occur in regard to sex morality. Moral 'inhibitions' in this field, more than in any other zone of natural morality, are likely to be qualified by the humanitarian critic as superstitious, obsolete, 'hostile to life,' and 'opposed to happiness.' The reason is obvious. 'Lust'--that is, inordinate sexual pleasure--typifies, in the most exemplary and characteristic manner, the concept of 'sin' as such; and the valuation of purity is the very touchstone of 'material' (essential, intrinsic, objective) ethics. In other words, 'lust' comes nearest to the idea of a material element of life--or a state of mind--'evil by itself' (the word impure is meant to express this) rather than evil on account of its impeding the gratification of more imperative needs or impinging upon more inviolable rights. . . .
"On the other hand, sex immorality--in its isolated typical forms, uncomplicated by violence or deceit--fails to involve any transgression of the 'rights of others,' or even any damage to their interests; in an immanent computation of 'human needs,' therefore, we may easily be driven to decide that those needs in their entirety are better served by disregarding certain 'needs for chastity' than by refusing gratification to certain, more or less vehement, sensual needs proscribed by religious or traditional morality. Humanitarian ethics will, without doubt, acknowledge and stress the elementary necessity of self-control and the general readiness to exercise it; but apart from this abstract and formal postulate, definite standards of purity can hardly count on any support. The individual and social 'harmfulness' of inordinate sexual pleasure as such being susceptible of a very vague and circuitous demonstration only, it will appear 'rational' to entrust its indulgence or shunning to anybody's personal taste--and more than that, to denounce any emphatic moral standpoint and terminology in these matters as intolerant, superstitious, narrow-minded, arbitrary, and obnoxious."
Aurel Kolnai, "The humanitarian versus the religious attitude," The Thomist 7, no. 4 (October 1944): 449-451. Note that "material" in quotation marks means something other than material without them. The former Kolnai associates with the religious tradition of moral reasoning, but the latter, neutral in itself, with the generation of those "needs" that "irreligious humanitarianism" is so reductively concerned to satisfy. I was especially struck by the contemporary relevance of that portion of these paragraphs beginning "The individual and social 'harmfulness' of inordinate sexual pleasure as such being susceptible of a very vague and circuitous demonstration only, . . ." (But the topic is taken up from "On the other hand, . . .")