The founding of such an establishment has been termed a scientific aberration, but the use now made in medical practice of oxygen, nitrous oxide, chloroform, and other inhalations bears witness to the sanity of the sort of research there set on foot.
— from An Introduction to the History of Science by Walter Libby

These principles, duly developed, are the true basis of morals; nothing is more chimerical than those which are founded upon imaginary motives placed out of nature; or upon innate sentiments; which some speculators have regarded as anterior to man's experience; as wholly independant of those advantages which result to him from its use: it is the essence of man to love himself; to tend to his own conservation; to seek to render his existence happy: thus interest, or the desire of happiness, is the only real motive of all his actions; this interest depends upon his natural organization, rests itself upon his wants, is bottomed upon his acquired ideas, springs from the habits he has contracted: he is without doubt in error, when either a vitiated organization or false opinions shew him his welfare in objects either useless or injurious to himself, as well as to others; he marches steadily in the paths of virtue when true ideas have made him rest his happiness on a conduct useful to his species; in that which is approved by others; which renders him an interesting object to his associates.
— from The System of Nature, or, the Laws of the Moral and Physical World. Volume 1 by Holbach, Paul Henri Thiry, baron d'