§8. What, then, is the conduct which Purity forbids (for the principle is more easily discussed in its negative aspect)? As the normal and obvious end of sexual intercourse is the propagation of the species, some have thought that all indulgence of appetite, except as a means to this end, should be prohibited. But this doctrine would lead to a restriction of conjugal intercourse far too severe for Common Sense. Shall we say, then, that Purity forbids such indulgence except under the conditions of conjugal union defined by Law? But this answer, again, further reflection shows to be unsatisfactory. For, first, we should not, on consideration, call a conjugal union impure, merely because the parties had wilfully omitted to fulfil legal conditions, and had made a contract which the law declined to enforce. We might condemn their conduct, but we should not apply to it this notion. And, secondly, we feel that positive law may be unfavourable to Purity, and that in fact Purity, like Justice, is something which the law ought to maintain, but does not always. We have to ask, then, what kind of sexual relations we are to call essentially impure, whether countenanced or not by Law and Custom? There appear to be no distinct principles, having any claim to self-evidence, upon which the question can be answered so as to command general assent. It would be difficult even to state such a principle for determining the degree of consanguinity between husband and wife which constitutes a union incestuous; although the aversion with which such unions are commonly regarded is a peculiarly intense moral sentiment; and the difficulty becomes indefinitely greater when we consider the rationale of prohibited degrees of affinity. Again, probably few would stigmatise a legal polygynous connexion as impure, however they might disapprove of the law and of the state of society in which such a law was established: but if legal Polygyny is not impure, is Polyandry, when legal and customary---as is not unfrequently the case among the lower races of man---to be so characterised? and if not, on what rational principle can the notion be applied to institutions and conduct? Again, where divorce by mutual consent, with subsequent marriage, is legalised, we do not call this an offence against Purity: and yet if the principle of free change be once admitted, it seems paradoxical to distinguish purity from impurity merely by less rapidity of transition; and to condemn as impure even `Free Love', in so far as it is earnestly advocated as a means to a completer harmony of sentiment between men and women, and not to mere sensual license.
Shall we, then, fall back upon the presence of mutual affection (as distinguished from mere appetite) as constituting the essence of pure sexual relations? But this, again, while too lax from one point of view, seems from another too severe for Common Sense: as we do not condemn marriages without affection as impure, although we disapprove of them as productive of unhappiness. Such marriages, indeed, are sometimes stigmatised as ``legalised prostitution'', but the phrase is felt to be extravagant and paradoxical; and it is even doubtful whether we do disapprove of them under all circumstances; as (e.g.) in the case of royal alliances.
Again, how shall we judge of such institutions as those of Plato's Commonwealth, establishing community of women and children, but at the same time regulating sexual indulgence with the strictest reference to social ends? Our habitual standards seem inapplicable to such novel circumstances.
The truth seems to be, that reflection on the current sexual morality discovers to us two distinct grounds for it: first and chiefly, the maintenance of a certain social order, believed to be most conducive to the prosperous continuance of the human race: and, secondly, the protection of habits of feeling in individuals believed to be generally most important to their perfection or their happiness. We commonly conceive that both these ends are to be attained by the same regulations: and in an ideal state of society this would perhaps be the case: but in actual life there is frequently a partial separation and incompatibility between them. But further, if the repression of sexual license is prescribed merely as a means to these ends, it does not seem that we can affirm as self-evident that it is always a necessary means in either case: on the contrary, it seems clear that such an affirmation would be unreliable apart from empirical confirmation. We cannot reasonably be sure, without induction from sociological observations, that a certain amount of sexual license will be incompatible with the maintenance of population in sufficient numbers and good condition. And if we consider the matter in its relation to the individual's perfection, it is certainly clear that he misses the highest and best development of his emotional nature, if his sexual relations are of a merely sensual kind: but we can hardly know a priori that this lower kind of relation interferes with the development of the higher (nor indeed does experience seem to show that this is universally the case). And this latter line of argument has a further difficulty. For the common opinion that we have to justify does not merely condemn the lower kind of development in comparison with the higher, but in comparison with none at all. Since we do not positively blame a man for remaining celibate (though we perhaps despise him somewhat unless the celibacy is adopted as a means to a noble end): it is difficult to show why we should condemn---in its bearing on the individual's emotional perfection solely---the imperfect development afforded by merely sensual relations.