In 1847 the Prussian government sent a young doctor to Upper Silesia to explain a typhus epidemic among the region's Polish-speaking poor. Virchow came back with a 190-page report that barely discussed drugs. The epidemic, he argued, was produced by hunger, ignorance and powerlessness, and its causes were the policies of the government that had commissioned him. His prescriptions were full and unlimited democracy, education, freedom and prosperity. Eight days after returning to Berlin, in March 1848, revolution broke out and he joined it. That July he helped found a weekly, Die Medizinische Reform, published under two banners: medicine is a social science, and the physician is the natural attorney of the poor. The paper was closed by June 1849 and he lost his post at the Charité. Würzburg gave him Germany's first chair of pathological anatomy instead. The Charité took him back in 1856.

His science was built on a single, disciplined idea: disease happens in cells, and to understand it you look. Cellular Pathology, published in 1858, is where modern pathology begins, and its slogan - omnis cellula e cellula, every cell from a cell - killed off the last respectable version of spontaneous generation. The credit is genuinely complicated. The epigram was coined by François-Vincent Raspail, and the evidence for cell division came from Robert Remak, whose work Virchow initially doubted and then, in 1855, published as his own, ending their friendship. What was unambiguously his fills a medical dictionary: he named leukemia in 1847, described chordoma in 1857, coined embolism and thrombosis, worked out how a clot in a leg vein reaches the lung, developed the first systematic method of autopsy, and traced the life cycle of the roundworm Trichinella spiralis - which is why meat inspection exists, adopted first in Berlin.

He meant the politics. Virchow sat on Berlin's municipal council from 1859 and was elected to the Prussian House of Representatives in 1862, later winning a Reichstag seat, and he co-founded the liberal German Progress Party. From 1869 he worked with the engineer James Hobrecht to give Berlin what it conspicuously lacked: a sewer system and a central water supply. The scheme drained the city through twelve independent radial systems out to irrigation fields beyond the built-up area - the cleanest available solution to urban sewage at the time, and a larger contribution to Berliners' life expectancy than any operation he ever performed. His opposition to Bismarck's finances provoked a challenge to a duel from the chancellor. He was not consistently on the liberal side of everything: he backed Bismarck's campaign against the Catholic Church, and gave it the name it still carries, Kulturkampf.

Virchow founded the German Anthropological Association in 1869 and the Berlin Society for Anthropology, Ethnology and Prehistory in 1870, at exactly the moment when European anthropology was hardening from measurement into ideology. He used the discipline against itself. The schoolchildren survey was designed to test whether a distinct German type and a distinct Jewish type could be found in the population, and its answer was no - both groups were overwhelmingly mixed, and neither could be sorted by appearance. At the anthropology congress in Karlsruhe in 1885 he denounced what he called the Nordic mysticism surrounding Aryan race theory. He opposed rising antisemitism directly, argued for minority rights, and dismissed Haeckel's social Darwinism as politically dangerous and anti-democratic. He was arguing with the future, and losing, and he knew it.

He was also capable of being magnificently, stubbornly wrong. He rejected germ theory and Semmelweis's insistence on disinfection. He called Darwin an ignoramus and his own former student Haeckel a fool. Examining the original Neanderthal skeleton in 1872, he ruled it an ordinary human deformed by rickets and arthritis, which set European palaeoanthropology back by years - and then joined Schliemann's expedition to Troy in 1879 and published on the skulls found there. The one case where posterity has moved back toward him is his most notorious. Called in on Kaiser Frederick III's throat, he examined the 1887 biopsy and insisted it was not cancer; he was accused of malpractice for a century. The Kaiser is now thought to have had hybrid verrucous carcinoma, a form nobody could identify until 1948. On 4 January 1902 Virchow fell jumping from a moving streetcar on Leipziger Straße and broke his femur. He never recovered, and died on 5 September. He lies in an honorary grave in the Alter St.-Matthäus-Kirchhof in Schöneberg.