cesses. The real significance of such aberrations-would reveal the difference between natural appetites and abnormal (artificially acquired) appetencies, and teach us the necessity of applying the tests of that distinction to all persuasive instincts, and occasionally to otherwise unexplained aversions.
But even within those limits a critical study of our protective intuitions would surprisingly show in how many respects the hygienic reforms of the last two hundred years could have been anticipated by the simple teachings of our senses. For the wards of instinct a temperance sermon would be as superfluous as a lecture on the folly of drinking boiling petroleum, for to the palate of a normal living being—human or animal—alcohol is not only unattractive, but violently repulsive, and the baneful passion to which that repugnance can be forced to yield is so clearly abnormal that only the infatuation of the natural depravity dogma could ever mistake it for an innate appetite. In defense of the respiratory organs. Nature fights almost to the last. The blinded dupe of the night-air superstition would hardly assert that he finds the hot miasma of his unventilated bedroom more pleasant than fresh air. He thinks it safer, in spite—or perhaps because—of its repulsiveness. "Mistrust all pleasant things" was the watchword of the mediaeval cosmogony. Long before Jahn and Pestalozzi demonstrated the hygienic importance of gymnastics, children embraced every opportunity for outdoor exercise with a zeal which only persistent restraint could abate. Sexual aberrations are a consequence, oftener than a cause, of disordered health. Instinct has always opposed the abuse of drugs, the delusions of asceticism, the suicidal follies of fashion. Instinct has never ceased to urge the reforms which our times have at last reached by such circuitous roads, and the study of its pleadings and protests might shorten those roads for the leaders of future generations.
On the other hand, it must be admitted that perverted appetites can become as irresistible as the most urgent natural instincts. Nor can it be denied that in some exceptional cases Nature fails to advise us of perils which her warning could easily avert, though we should remember that her standards of expediency are not always our own, and that, as a rule, instinct asserts itself at the fittest times, and with an urgency proportionate to the importance of its mission.
The exceptions, thus far only partly explained, may be summed up under the three following heads: 1. Perverted Instincts.—The physiology of certain abnormal propensities is as obscure as the origin of sin. There is no doubt that the innate aversion to any poison known to modern chemistry can, by persistent disregard, be turned into a morbid appetency, vehement and persistent in proportion to the virulence of the poison. The most plausible hypothesis suggested in explanation of that fact seems to be the conjecture that, in adapting itself to the exigencies of abnormal circumstances, the constitution of the
