The philosopher, in asking himself the question, _what is love_, solves it by asking another question, _what is an animal_, or _what is man?_ Looking at mankind, he finds them of two classes, male and female, varying but little as to external form or internal character. He finds that they possess the same passions, the same desires, that they live by the same means, and with the difference of the female being the body qualified to breed the species, he sees them in every respect to be exactly alike. Reproduction or accumulation of identities similar to self is a common law of animal and vegetable matter; and the disposition to reproduce in all well-formed and healthy subjects is as powerful as hunger, or thirst, or the desire of self-preservation. It is a passion not criminal in the indulgence, but criminality attaches where the indulgence is withheld; because health, and even life, is endangered. It is not an artificial passion, such as a craving to exhibit the distinctions of society; but a natural passion, which we hold in common with every other animal. It grows with our growth, and is strengthened with our strength. To prove that genuine love is nothing but this passion, it is sufficient to refer to the period at which it comes on, and at which it leaves us. We hear not of love in decaying age or in infancy; and the attachments of habit, of kindness, of gratitude, or of human, social, individual, parental, filial, or domestic affection, have no connexion with the passion of love. We talk of a love, of virtue, of friendship, of heroism, of character, of generosity; but this kind of love is a matter wholly distinct from the passion of love between the male and female. All men are apt to feel the tender passion of love for a beautiful woman: all women for a handsome and agreeable man: but this is nothing more than a desire to associate ourselves with the most agreeable objects for sexual commerce. The every day occurrences of mankind explain this matter, and hence the many violences and intrigues connected with the passion of love; hence seductions, adulteries, rapes and intercourses pronounced unlawful in different countries. The present purpose of this work is, to explain the physiology of the reproductive organs, and the social bearing that a proper control of the reproductive instinct will have upon society, and its consequences when uncontrolled, and the benefits that must necessarily accrue when kept under due restraint. Chemical science and experimental investigation, aided by the recent discoveries in that department of literature, have enabled the Editor to offer to the suffering mother a safe and sure preventive of conception. The expediency and moral propriety of its use he trusts will be satisfactorily explained in the subsequent pages. MORAL PHYSIOLOGY.