What manifests itself in the individual consciousness as instinct of sex in general, without being concentrated on any particular individual, is very plainly in itself, in its generalised form, the will to live. On the other hand, that which appears as instinct of sex directed to a certain individual, is in itself the will to live as a definitely determined individual. In this case the instinct of sex very cleverly wears the mask of objective admiration, although in itself it is a subjective necessity, and is, thereby, deceptive. Nature needs these stratagems in order to accomplish her ends. The purpose of every man in love, however objective and sublime his admiration may appear to be, is to beget a being of a definite nature, and that this is so, is verified by the fact that it is not mutual love but possession that is the essential. Without possession it is no consolation to a man to know that his love is requited. In fact, many a man has shot himself on finding himself in such a position. On the other hand, take a man who is very much in love; if he cannot have his love returned he is content simply with possession. Compulsory marriages and cases of seduction corroborate this, for a man whose love is not returned frequently finds consolation in giving handsome presents to a woman, in spite of her dislike, or making other sacrifices, so that he may buy her favour.
The real aim of the whole of love's romance, although the persons concerned are unconscious of the fact, is that a particular being may come into the world; and the way and manner in which it is accomplished is a secondary consideration. However much those of lofty sentiments, and especially of those in love, may refute the gross realism of my argument, they are nevertheless in the wrong. For is not the aim of definitely determining the individualities of the next generation a much higher and nobler aim than that other, with its exuberant sensations and transcendental soap-bubbles? Among all earthly aims is there one that is either more important or greater? It alone is in keeping with that deep-rooted feeling inseparable from passionate love, with that earnestness with which it appears, and the importance which it attaches to the trifles that come within its sphere. It is only in so far as we regard this end as the real one that the difficulties encountered, the endless troubles and vexations endured, in order to attain the object we love, appear to be in keeping with the matter. For it is the future generation in its entire individual determination which forces itself into existence through the medium of all this strife and trouble. Indeed, the future generation itself is already stirring in the careful, definite, and apparently capricious selection for the satisfaction of the instinct of sex which we call love. That growing affection of two lovers for each other is in reality the will to live of the new being, of which they shall become the parents; indeed, in the meeting of their yearning glances the life of a new being is kindled, and manifests itself as a well-organised individuality of the future. The lovers have a longing to be really united and made one being, and to live as such for the rest of their lives; and this longing is fulfilled in the children born to them, in whom the qualities inherited from both, but combined and united in one being, are perpetuated. Contrarily, if a man and woman mutually, persistently, and decidedly dislike each other, it indicates that they could only bring into the world a badly organised, discordant, and unhappy being. Therefore much must be attached to Calderon's words, when he calls the horrible Semiramis a daughter of the air, yet introduces her as a daughter of seduction, after which follows the murder of the husband.
Finally, it is the will to live presenting itself in the whole species, which so forcibly and exclusively attracts two individuals of different sex towards each other. This will anticipates in the being, of which they shall become the parents, an objectivation of its nature corresponding to its aims. This individual will inherit the father's will and character, the mother's intellect, and the constitution of both. As a rule, however, an individual takes more after the father in shape and the mother in stature, corresponding to the law which applies to the offspring of animals.... It is impossible to explain the individuality of each man, which is quite exceptional and peculiar to him alone; and it is just as impossible to explain the passion of two people for each other, for it is equally individual and uncommon in character; indeed, fundamentally both are one and the same. The former is explicite what the latter was implicite.
We must consider as the origin of a new individual and true punctum saliens of its life the moment when the parents begin to love each other—to fancy each other, as the English appropriately express it. And, as has been said, in the meeting of their longing glances originates the first germ of a new being, which, indeed, like all germs, is generally crushed out. This new individual is to a certain extent a new (Platonic) Idea; now, as all Ideas strive with the greatest vehemence to enter the phenomenal sphere, and to do this, ardently seize upon the matter which the law of causality distributes among them all, so this particular Idea of a human individuality struggles with the greatest eagerness and vehemence for its realisation in the phenomenal. It is precisely this vehement desire which is the passion of the future parents for one another. Love has countless degrees, and its two extremes may be indicated as Ἀφροδιτη πανδημος and οὐρανια; nevertheless, in essentials it is the same everywhere.
According to the degree, on the other hand, it will be the more powerful the more individualised it is—that is to say, the more the loved individual, by virtue of all her qualities, is exclusively fit to satisfy the lover's desire and needs determined by her own individuality. If we investigate further we shall understand more clearly what this involves. All amorous feeling immediately and essentially concentrates itself on health, strength, and beauty, and consequently on youth; because the will above all wishes to exhibit the specific character of the human species as the basis of all individuality. The same applies pretty well to everyday courtship (Ἀφροδιτη πανδημος). With this are bound up more special requirements, which we will consider individually later on, and with which, if there is any prospect of gratification, there is an increase of passion. Intense love, however, springs from a fitness of both individualities for each other; so that the will, that is to say the father's character and the mother's intellect combined, exactly complete that individual for which the will to live in general (which exhibits itself in the whole species) has a longing—a longing proportionate to this its greatness, and therefore surpassing the measure of a mortal heart; its motives being in a like manner beyond the sphere of the individual intellect. This, then, is the soul of a really great passion. The more perfectly two individuals are fitted for each other in the various respects which we shall consider further on, the stronger will be their passion for each other. As there are not two individuals exactly alike, a particular kind of woman must perfectly correspond with a particular kind of man—always in view of the child that is to be born. Real, passionate love is as rare as the meeting of two people exactly fitted for each other. By the way, it is because there is a possibility of real passionate love in us all that we understand why poets have depicted it in their works.
Because the kernel of passionate love turns on the anticipation of the child to be born and its nature, it is quite possible for friendship, without any admixture of sexual love, to exist between two young, good-looking people of different sex, if there is perfect fitness of temperament and intellectual capacity. In fact, a certain aversion for each other may exist also. The reason of this is that a child begotten by them would physically or mentally have discordant qualities. In short, the child's existence and nature would not be in harmony with the purposes of the will to live as it presents itself in the species.
In an opposite case, where there is no fitness of disposition, character, and mental capacity, whereby aversion, nay, even enmity for each other exists, it is possible for love to spring up. Love of this kind makes them blind to everything; and if it leads to marriage it is a very unhappy one.
And now let us more thoroughly investigate the matter. Egoism is a quality so deeply rooted in every personality that it is on egotistical ends only that one may safely rely in order to rouse the individual to activity.
To be sure, the species has a prior, nearer, and greater claim on the individual than the transient individuality itself; and yet even when the individual makes some sort of conscious sacrifice for the perpetuation and future of the species, the importance of the matter will not be made sufficiently comprehensible to his intellect, which is mainly constituted to regard individual ends.
Therefore Nature attains her ends by implanting in the individual a certain illusion by which something which is in reality advantageous to the species alone seems to be advantageous to himself; consequently he serves the latter while he imagines he is serving himself. In this process he is carried away by a mere chimera, which floats before him and vanishes again immediately, and as a motive takes the place of reality. This illusion is instinct. In most instances instinct may be regarded as the sense of the species which presents to the will whatever is of service to the species. But because the will has here become individual it must be deceived in such a manner for it to discern by the sense of the individual what the sense of the species has presented to it; in other words, imagine it is pursuing ends concerning the individual, when in reality it is pursuing merely general ends (using the word general in its strictest sense).