into hysteria, and vice versâ; or lypemania will take the place of pulmonary consumption, hysteria, hypochondria, epilepsy.

To sum up briefly what has been said: M. Lemoine, in his study on Morbid Psychology, has made a very just criticism on this resort to two laws, the one of spontaneity and the other of heredity, both reciprocally supplying each other's defects. 'When the one is at fault,' says he, and puts the system in danger of failure, the other is hastily adduced, and everything is set right with a word. A madman's son is a madman: the law of heredity is invoked to explain his insanity. An idiot is born of parents and descends from ancestors who are all of sound body and mind: spontaneity is invoked to account for the fact.' We hold, with Lemoine, that spontaneity thus understood is an occult quality, an explanation that explains nothing, like the Quia est in eo virtus dormitiva.

But M. Lemoine, speaking of the reduction of spontaneity to heredity, adds: 'The reduction of these two laws to one is rather ingenious than legitimate, for it appears to me that the law of spontaneity should rather absorb the law of heredity. If we ascend from generation to generation, we certainly do not always find lunatics the children of lunatics, or idiots the children of epileptics. But at length we shall be more fortunate; probably in the distant past, not so far back as the deluge, we shall find a lunatic, or epileptic, or idiot, who is the child of parents and ancestors, sound of mind and body-in short, an idiosyncrasy. This idiosyncrasy, whatever it may be, is the starting-point, is the pattern after which nature has fashioned all the descending generations. In creating this first case of disease, whensoever it appeared, nature acted freely. On the contrary, when she transmits disease as a heritage from fathers tó children, she does but imitate herself, and copy her own model. The law of spontaneity explains the law of heredity, instead of being explained by it, if, indeed, it explains anything.'

To our mind there is here a confusion of two questions, which it is important for us to notice: a metaphysical question regarding the first cause, and a scientific question concerning secondary

causes.

If we take metaphysical and transcendental ground-which we

do not here propose to do-spontaneity undoubtedly takes precedence of heredity, since it is clear that the derivative presupposes the primitive, and the imitation presupposes the model.

But if, as now, we take our stand on the ground of science and experiment, heredity becomes the only law; for it alone has a character of constancy, fixedness; and because it alone is reducible to formulas. Whether we admit with Lamarck the spontaneity of a single type, or with Darwin of three or four types, or of a very great number with Cuvier, so soon as we quit that region of origins and enter the domain of experience we see that nothing subsists except by heredity.

We have, therefore, to return to our starting-point. Heredity is the law. It is no à priori conception, any more than the axiom, like produces like. It is the accumulated and generalized result of an innumerable mass of experiences. Facts prove that between the partus and the parens there is never anything more than individual differences, and that the immense majority of characteristics is always inherited. Thus, according to the standpoint which we take, it is equally true to say that the law of heredity is always realized, and that it is never realized. The heredity of the greater share of the characteristics is a thing of universal occurrence; but the heredity of the sum of all the characteristics is never found. So that heredity, while it is the law, is always the exception. But no argument can be drawn from this; for it is a logical necessity that where the conditions of a law are not completely realized the law cannot attain its ideal.

PART THIRD.

THE CAUSES.

Die Materialisten bemühen sich zu zeigen dass alle Phænomene, auch die geistigen, physisch sind: mit Recht; nur sehen sie nicht ein, dass alles Physiche andererseits zugleich ein Metaphysisches ist.—Schopenhauer.

CHAPTER I.

GENERAL RELATIONS BETWEEN THE PHYSICAL AND THE MORAL.

I.

To inquire into causes we must hazard hypotheses. This cannot be avoided; for though science begins with the investigation of laws, it is perfected only in the determination of causes. Here, too, as in every experimental study, we have only to deal with secondary and immediate causes, or, in plainer terms, with invariable antecedents. As far as our purpose is concerned, to explain physiological heredity means to define an aggregate of conditions, of such a nature that if these conditions are present heredity necessarily follows, and when they are wanting heredity is invariably wanting. In what follows, therefore, there is no question of ultimate causes; and, without inquiring here whether they are accessible or inaccessible to the human mind, we shall never speak of them except with the admission that we are entering on hypotheses.

Heredity is only a special case of the great problem of the relations between physics and morals, as will more clearly appear in the course of this work. We can, however, note in advance, in a more precise way, the position of our question, by observing that every inquiry into the relations between physics and morals necessarily comprises two parts, the influence of the moral on the physical, and the influence of the physical on the moral. The problem of heredity is concerned only with the latter. The influence of physics on morals manifests itself in many ways, of which we here consider one only, heredity. With this explanation we can now indicate the line of inquiry we shall follow in our study of causes.

We shall, in the first place, examine in a very general way the relations between the physical and the moral, as the problem in its most general form necessarily governs all the particular cases.