It appears to me that the greater tendency to confound science and art, when the subject is mind, than when it is matter, arises from the more immediate influence on human conduct possessed by the mental sciences. The sciences which consider matter have often little apparent connection with any of the arts to which they are subservient. The application of chemistry to agriculture has taken place almost within our own recollection; its application to navigation is still more recent; to transport by land, more recent still; to the transmission of intelligence, scarcely ten years old. Such sciences may be, and indeed generally are, most earnestly studied by men who have no object beyond the discovery and diffusion of truth. That object is enough to satisfy the most ardent scientific ambition, and to urge the most unwearied scientific labours. The astronomer does not consider what will be the practical results of his inquiries, or whether they will lead to any practical results whatever. His object is knowledge. The uses to which that knowledge may be applied, the mode and the degree in which it may affect men’s conduct, he leaves to others. On the other hand, the mental sciences are directly and obviously connected with the arts of which they furnish the principles; and those arts almost every educated man must practise. No man studies the science of reasoning without resolving to apply its principles whenever he has to exercise the art of controversy. No man inquires into the laws which regulate the human intellect or the human passions, without framing out of them some practical rules for the employment of his own faculties and the regulation of his own affections. The distinction between physical and mental is important, not only with respect to the subjects treated by the sciences and arts in each class, but also with respect to the principal sources from which they respectively draw their premises.