Moral sensibility undergoes the same developmental movement ; intelligence and memory enrich these first manifestations every instant.
Henceforward the first links of family affection bind themselves round his heart, and thus become the origin of his first sentiments and emotions. He loves those who approach him, for the sake of the good things they have already done for him. He can recognize those who wish him well or ill, or who are simply indifferent to him ; and thus it is that to every one who comes in contact with him, and excites his sensibility in one way or another, he devotes an appropriate memory and a gratitude propor tioned to the good or evil influence he has received. He loves his parents, in the first place, because they contribute more or less to his well-being and his plea sures, and because he is in the habit of seeing them every day ; and this incessant renewal of physical im pressions keeps the sentiment of gratitude in a condition of permanence and freshness in his sensorium. Those who are always present before his eyes are similarly present in his heart.
At another period of human existence, the most violent of the sentiments which are calculated to set all the sensitive chords of the living being vibrating—love —develops itself merely by virtue of the same physio logical laws.
It is at its outset, as in the young child, the satisfac tion of physical sensibility which forms the necessary prelude to it, its first stage and indispensable condition.
It is because he has been thrilled in all the elements of his physical sensibility that the living creature, at the period of love, is inevitably hurried forward, by invin cible hereditary impulses, towards the being destined to be his complement and to become the physiological receptacle of his deepest joys.
It is because he has been charmed at once, in all the sensitive elements of his being, by the sight of the plastic beauties of the object of his desires, by the seductions of her speech, her voluptuous contact, and all her intellectual and moral wealth, that he is cap tivated and subdued. It is because all his physical sensibilities have been simultaneously awakened, and that a period of generalized erethism is developed in his sensorium, that he loves the object who has been for him the origin of all his happiness—that he attaches himself to her, becomes her slave, and surrenders him self altogether ; just as, when he was a child, he loved, according to the measure of affection of which he was capable, the nurse who gratified his first sensuous appetites.
Thus it is that love, the concrete expression of all the sensibilities thrown into agitation, develops itself in the living being as a recognition of physical pleasures satisfied, and as a hope of their repetition ; and that this sentiment, so simple in rudimentary organisms, in which sensibility is little developed, becomes corfipli cated in the animal series in proportion as the sum of the sensitive elements multiplies, arid the phenomena of moral sensibility come more into play.
In fact, in proportion as we pursue the study of this sentiment through the series of living creatures, we see -• that, by slow gradations, it undergoes a progressive transformation, and that in proportion as the moral influences of civilization become paramount, the purely animal physical love of savage peoples loses its primi tive character, to become clothed in new forms, appro priate to the new medium in which it is developed.
Thus it is that polygamy, which is the social expres sion of the satisfaction of all physical pleasures, insen sibly gives place to monogamy, the most perfect expression of the union of the man and woman, and a more serious guarantee for the maintenance of the family. This regular form of love, which is an epitome of the most delicate perfections of human sensibility, concentrates upon a single head the sorrows and joys of the past and the hopes of the future, and thus cements the permanent ties consecrated by the customs of common life. It inevitably engenders, in every degree of the social scale, spite of the numerous short comings by which it is dishonoured, those natural acts of devotion and self-abnegation for the common work of progeniture, and that whole series of respectable senti ments of which the domestic morality of monogamous peoples offers most striking examples.
As a man advances in life, his sensibility becomes gradually -lessened—the senses become dull, the sight loses its sharpness, the skin its impressionability by ex ternal agents.* A sort of general slackening of all his functions impends over the living creature thus arrived at the retrogade phases of his evolution.
This condition of diminution of the peripheral sensi bility is reflected in a similar manner upon the sensibility of the central regions. Moral impressionability and emotil ity lose their energy as a man grows old. He is less and less interested in external things capable of exciting his mental activity. He is less sensitive, less impressionable, less curious as to knowledge and feeling, and at the same time his intellectual faculties are simultaneously impaired. Memories of the past, like enfeebled phosphoric gleams, persist for a certain time, to the exclusion of more recent remembrances, but, in the end, even they too are extinguished, SQ that, the circle of bygone things narrowing by degrees, the indi vidual feeds his sensorium only with the current opera tions of life. Material life with all its necessities— eating, drinking, and sleeping, becomes, little by little, the favourite occupation of organisms in the period of decadence ; and as to moral sensibility, the old man, an egotist with few exceptions, is reduced to vegetative life, and becomes once more a child, caring no longer for those who care for him day after day. He forgets his old friends, and the most natural family affections, for the sake of the newest comer, and succumbing more and more to the interested demands of his personality, he arrives, as regards moral sensibility, at a true anws thesia which reflects the languishing condition of the elements of his nervous activity.