Even in the 18th century the search for a simple way of healing the sick continued. In Edinburgh the writer and lecturer John Brown expounded his view that there were only two diseases, sthenic (strong) and asthenic (weak), and two treatments, stimulant and sedative; his chief remedies were alcohol and opium. Lively and heated debates took place between his followers, the Brunonians, and the more orthodox Cullenians (followers of William Cullen, a professor of medicine at Glasgow), and the controversy spread to the medical centres of Europe.

At the opposite end of the scale, at least in regard to dosage, was Samuel Hahnemann, of Leipzig, the originator of homeopathy, a system of treatment involving the administration of minute doses of drugs whose effects resemble the effects of the disease being treated. His ideas had a salutary effect upon medical thought at a time when prescriptions were lengthy and doses were large, and his system has had many followers.

By the 18th century the medical school at Leiden had grown to rival that of Padua, and many students were attracted there from abroad. Among them was John Monro, an army surgeon, who resolved that his native city of Edinburgh should have a similar medical school. He specially educated his son Alexander with a view to having him appointed professor of anatomy, and the bold plan was successful. Alexander Monro studied at Leiden under Hermann Boerhaave, the central figure of European medicine and the greatest clinical teacher of his time. Subsequently, three generations of the Monro family taught anatomy at Edinburgh over a continuous period of 126 years. Medical education was increasingly incorporated into the universities of Europe, and Edinburgh became the leading academic centre for medicine in Britain.

In 18th-century London, Scottish doctors were the leaders in surgery and obstetrics. The noted teacher John Hunter conducted extensive researches in comparative anatomy and physiology, founded surgical pathology, and raised surgery to the level of a respectable branch of science. His brother William Hunter, an eminent teacher of anatomy, became famous as an obstetrician. Male doctors were now attending women in childbirth, and the leading obstetrician in London was William Smellie. His well-known Treatise on the Theory and Practice of Midwifery, published in three volumes in 1752–64, contained the first systematic discussion on the safe use of obstetrical forceps, which have since saved countless lives. Smellie placed midwifery on a sound scientific footing and helped to establish obstetrics as a recognized medical discipline.

The science of modern pathology also had its beginnings in this century. Giovanni Battista Morgagni, of Padua, in 1761 published his massive work De Sedibus et Causis Morborum (The Seats and Causes of Diseases Investigated by Anatomy), a description of the appearances found by postmortem examination of almost 700 cases, in which he attempted to correlate the findings after death with the clinical picture in life.

On the basis of work begun in the 18th century, René Laënnec, a native of Brittany, who practiced medicine in Paris, invented a simple stethoscope, or cylindre, as it was originally called. In 1819 he wrote a treatise, De l’auscultation médiate (“On Mediate Auscultation”), describing many of the curious sounds in the heart and lungs that are revealed by the instrument. Meanwhile, a Viennese physician, Leopold Auenbrugger, discovered another method of investigating diseases of the chest, that of percussion. The son of an innkeeper, he is said to have conceived the idea of tapping with the fingers when he recalled that he had used this method to gauge the level of the fluid contents of his father’s casks.

One highly significant medical advance, late in the century, was vaccination. Smallpox, disfiguring and often fatal, was widely prevalent. Inoculation, which had been practiced in the East, was popularized in England in 1721–22 by Lady Mary Wortley Montagu, who is best known for her letters. She observed the practice in Turkey, where it produced a mild form of the disease, thus securing immunity although not without danger. The next step was taken by Edward Jenner, a country practitioner who had been a pupil of John Hunter. In 1796 Jenner began inoculations with material from cowpox (the bovine form of the disease). When he later inoculated the same subject with smallpox, the disease did not appear. This procedure—vaccination—has been responsible for eradicating the disease.

Public health and hygiene were receiving more attention during the 18th century. Population statistics began to be kept, and suggestions arose concerning health legislation. Hospitals were established for a variety of purposes. In Paris, Philippe Pinel initiated bold reforms in the care of the mentally ill, releasing them from their chains and discarding the long-held notion that insanity was caused by demon possession.

Conditions improved for sailors and soldiers as well. James Lind, a British naval surgeon from Edinburgh, recommended fresh fruits and citrus juices to prevent scurvy, a remedy discovered by the Dutch in the 16th century. When the British navy adopted Lind’s advice—decades later—this deficiency disease was eliminated. In 1752 a Scotsman, John Pringle, published his classic Observations on the Diseases of the Army, which contained numerous recommendations for the health and comfort of the troops. Serving with the British forces during the War of the Austrian Succession, he suggested in 1743 that military hospitals on both sides should be regarded as sanctuaries; this plan eventually led to the establishment of the Red Cross organization in 1864.

Two pseudoscientific doctrines relating to medicine emerged from Vienna in the latter part of the century and attained wide notoriety. Mesmerism, a belief in “animal magnetism” sponsored by Franz Anton Mesmer, probably owed any therapeutic value it had to suggestions given while the patient was under hypnosis. Phrenology, propounded by Franz Joseph Gall, held that the contours of the skull are a guide to an individual’s mental faculties and character traits; this theory remained popular throughout the 19th century.

At the same time, sound scientific thinking was making steady progress, and advances in physics, chemistry, and the biological sciences were converging to form a rational scientific basis for every branch of clinical medicine. New knowledge disseminated throughout Europe and traveled across the sea, where centres of medical excellence were being established in America.