John Brown, a Scottish physician, "founder of the Brunonian system, born in Berwickshire in 1735, died in London, Oct. 7, 1788. He was the son of a poor farmer, and was early apprenticed to a weaver; but having previously manifested much aptitude for study at the grammar school of Dunse, the schoolmaster offered to instruct him gratuitously. The schoolmaster and the parents of Brown belonged to a body of Presbyterian seceders, and young Brown was destined for the ministry. While pursuing his studies he was induced to attend a meeting of the synod of the established church at Dunse, and this gave such offence to his friends that he left the society and joined the established church. He then became private tutor in a gentleman's family, and acted as an assistant in the grammar school.. In 1755 he went to Edinburgh, and after passing through the preliminary classes, entered himself as a student of divinity in the university. For some time he supported himself by private teaching, and then resumed his labors as assistant teacher at Dunse, where he remained about a year. In 1759 he returned to Edinburgh, renounced the study of theology, and commenced that of medicine, supporting himself by giving private instruction in Latin to medical students.

Dr. Cullen employed him as a private tutor in his own family, and recommended him to others, but opposed his nomination to a professorship, whereupon Brown began to attack the doctor's medical views. Having quarrelled with the professors at Edinburgh, he took his degree of M. D. at St. Andrew's. In 1780 he published his Elementa Medicince, which contains the doctrines he propounded in opposition to the views of Dr. Cullen, and for several years he continued to explain these doctrines in public lectures. The excitement produced by this work was very great in all the medical schools of Europe; and in Edinburgh two hostile camps were formed among the students, under the names of " Oullenites " and "Brownites." The contest sometimes raged with so much violence as to lead to collisions among the younger partisans. In 1786 Brown went to London, where he opened a private school of medicine, and gave lectures in his own house in Golden square. His family was large, and his habits intemperate; his expenses were greater than his income, and being involved in debt, he was confined in the king's bench prison during several months, until released by the assistance of some of his friends.

His doctrines had gained many converts in the medical schools abroad, and he was making preparations to leave England for the continent, when he died of apoplexy. - The publication of his first work was followed in 1781 by " An Inquiry into the State of Medicine, on the Principles of the Inductive Philosophy." In 1787 he published "Observations on the Principles of the Old System of Physic." A complete edition of his works (3 vols. 8vo) was published in London by his son, William Cullen Brown, in 1804. The basis of Brown's medical theory is the doctrine of " excitability." In his view, the human organism, in common with that of animals, mainly differs from inorganic bodies by the property of being excited under the influence of external agents, or the functions of internal organs, peculiar to organic life. The physical external agents which excite the organism to act are heat, light, air, and alimentary substances; internally, the blood and the humors which are drawn from the blood. Those functions of the organs which produce a similar effect, according to this theory, are muscular contractions, the various secretions of the body, the passions, and the energy of the brain in the processes of thought.

These are what Brown terms the stimulating or exciting forces, which, collectively considered, produce life; and when this influence ceases, death ensues. The state of health consists in a proper equilibrium between the exciting forces and the vital principle of excitability within the organism; disease consists in the rupture of this equilibrium. Two kinds of excess may disturb the equilibrium of health, and hence all diseases may be classed under two general heads: those produced by an excess of the stimulating forces, and those resulting from an insufficiency of stimulation. The one are called " sthenic " (Gr. , strength), and the other " asthenic," from the want of force. The treatment consists in diminishing the excess of stimulus in one case, and supplying that which is deficient in the other. His doctrines became very popular for a time all over Europe. Gir-tanner spread them in Germany, and Rasori in Italy. Broussais developed similar views in another form, 30 years later, in France, attributing the origin of all diseases to inflammatory action in the organism, and substituting the word "irritability" in lieu of "excitability," but adopting Brown's division of all diseases into two classes, "sthenic and asthenic." The exaggerations of these two schools have lost their influence on many minds, but the words which mainly characterized their doctrines, as stimulants and contra-stimulants, irritability and excitability, sthenic and asthenic, are still common in the medical vocabulary.