The moral faculty has received different names from different authors. It is the "moral sense" of Dr. Hutchison; the "sympathy" of Dr. Adam Smith; the "moral instinct" of Rousseau; and "the light that lighter every man that cometh into the world" of St. John. I have adopted the term of moral faculty from Dr. Bettie, because I conceive it conveys with the most perspicuity, the idea of a capacity in the mind, of chasing good and evil. Our books of medicine contain many records of the effects of physical causes upon the memory, the imagination, and the judgment. In some instances we behold their operation only on one, in others on two, and, in many cases, upon the whole of these faculties. Their derangement has received different names, according to the number or nature of the faculties that are affected. The loss of memory has been called "amnesia;" false judgment upon one subject has been called "melancholia;" false judgment upon all subjects has been called "mania;" and a defect of all the three intellectual faculties that have been mentioned, has received the name of "amnesia." Persons who labour under the derangement, or want of these faculties of the mind, are considered, very properly, as subjects of medicine; and there are many cases upon record that prove, that their diseases have yielded to the healing art. In order to illustrate the effects of physical causes upon the moral faculty, it will be necessary _first_ to show their effects upon the memory, the imagination, and the judgment; and at the same time to point out the analogy between their operation upon the intellectual faculties of the mind, and the moral faculty. 1. Do we observe a connection between the intellectual faculties, and the degrees of consistency and firmness of the brain in infancy and childhood? The same connection has been observed between the strength, as well as the progress of the moral faculty in children. 2. Do we observe a certain size of the brain, and a peculiar cast of features, such as the prominent eye, and the aquiline nose, to be connected with extraordinary portions of genius? We observe a similar connection between the figure and temperament of the body, and certain moral qualities. Hence we often ascribe good temper and benevolence to corpulence, and irascibility to sanguineous habits. CA thought himself safe in the friendship of the "sleek-headed" Anthony and Willabella; but was afraid to trust to the professions of the slender Cassius. 3. Do we observe certain degrees of the intellectual faculties to be hereditary in certain families? The same observation has been frequently extended to moral qualities. Hence we often find certain virtues and vices as peculiar to families, through all their degrees of consanguinity, and duration, as a peculiarity of voice, complexion, or shape.