A differentiation of original and acquired cases of sadism is scarcely possible. Many individuals, tainted ab origine, for a long time do everything to conquer the perverse instinct. If they are potent, at first they are able to lead a normal vita sexualis, often with the assistance of subjective ideas of a perverse nature. Later, after the opposing motives of an ethical and æsthetic kind have been gradually overcome, and after the constantly repeated experience that the natural act does not bring complete satisfaction, the abnormal instinct bursts forth. Owing to this late expression, in acts, of an originally perverse disposition, the appearances are those of an acquired perversion. As a rule, it may be safely assumed that this psychopathic state exists ab origine.
Sadistic acts vary in monstrousness with variation in the power of the perverse instinct over the individual afflicted, and with variation in the strength of opposing ideas that may be present, which almost always are more or less weakened by original ethical defect, hereditary degeneracy, or moral insanity. Thus there arises a long series of forms which begins with capital crime and ends with silly acts which afford the perverse desires of the sadistic individual merely symbolic satisfaction.
Sadistic acts may be further differentiated with reference to their nature: either as they are indulged in after consummated coitus by which the libido nimia remains unsatisfied; or, with diminished virility, as they are used to stimulate the diminished power; or, finally, where virility is absolutely wanting, as they become an equivalent for the impossible coitus, for the induction of ejaculation. In the last two cases, notwithstanding the impotence, there is still intense libido; or there was, at least, intense libido in the individual at the time when the sadistic acts became habitual. Sexual hyperæsthesia is always to be regarded as the basis of sadistic inclinations. The impotence which occurs so frequently in the psychopathic and neuropathic individuals here considered, as a result of excesses indulged in from early youth, is usually dependent upon spinal weakness. Often, too, there is a kind of psychical impotence, induced by concentration of thought on the perverse act with
