"P. Ch. A. Louis, physician of the Hospital de la Pitié, is a man, whose labors and whose writings must become more and more known for ages. I should deem it service enough to my brethren in this country, if I could induce them, one and all, to read and study the works of this great pathologist. M. Louis is the founder of the numerical system, as it has been denominated, in respect to the science of medicine. ...M. Louis has not brought forward a new system of medicine; he has only proposed and pursued a new method in prosecuting the study of medicine. This is nothing else than the method of induction, the method of Bacon, so much vaunted and yet so little regarded. ...To estimate the value of his observations, it is necessary to understand the plan, on which he collected them. First, then, he ascertained when the patient under his examination began to be diseased. Not satisfied with vague answers, he went back to the period, when the patient enjoyed his usual health; and he also endeavored to learn whether that usual health had been firm, or in any respect infirm. He noted also the age, occupation, residence, and manner of living of the patient; likewise any accidents which had occurred, and which might have influenced the disease then affecting him. He ascertained also, as much as possible, the diseases which had occurred in the family of his patient. Secondly, he inquired into the present disease, ascertaining not only what symptoms had marked its commencement, but those which had been subsequently developed and the order of their occurrence; and recording those, which might not seem to be connected with the principal disease, as well as those which were so connected; also, measuring the degree or violence of each symptom, with as much accuracy as the case would admit. Thirdly, he noted the actual phenomena present at his examination, depending for this not only on the statement of the patient, but on his own senses, his eyes, his ears and his hands. Under this and the preceding head he was not satisfied with noting the functions, in which the patient complained of disorder, but examined carefully as to all the functions, recording their state as being healthy or otherwise, and even noticing the absence of symptoms, which might bear on the diagnosis. Thus all secondary diseases, and those, which accidentally co-existed with the principal malady, were brought under his view. Fourthly, he continued to watch his patient from day to day, carefully recording all the changes, which occurred in him till his restoration to health, or his decease. Fifthly, in the fatal cases he exercised the same scrupulous care in examining the dead, as he had in regard to the living subject. Prepared by a minute acquaintance with anatomy, and familiar with the changes wrought by disease, he looked not only at the parts where the principal disorder was manifested, but at all the organs. His notes did not state opinions, but facts. He recorded in regard to each part, which was not quite healthy in its appearance, the changes in color, consistence, firmness, thickness, &c.; not contenting himself with saying that a part was inflamed, or was cancerous, or with the use of any general, but indefinite terms."