Hendrik Antoon Lorentz was one of the greatest physicists and mathematicians the Netherlands has ever known. Einstein called him a living work of art, a perfect personality . During his funeral in 1928, the entire Dutch nation mourned. The national telegraph service was suspended for three minutes and his passing was national and international front-page news. The cream of international science, an impressive list of dignitaries, including the Prince Consort, and thousands of ordinary people turned out to see Lorentz being carried to his last resting place. This biography describes the life of Lorentz, from his early childhood, as the son of a market gardener in the provincial town of Arnhem, to his death, as a towering figure in physics and in international scientific cooperation and as a trailblazer for Einstein’s relativity theory. A number of chapters shed light on his unique place in science, the importance of his ideas, his international conciliatory and scientific activities after World War One, his close friendship with Albert Einstein, and his important role as Einstein’s teacher and intellectual critic. By making use of recently discovered family correspondence, the authors were able to show that there lies a true human being behind Lorentz’s facade of perfection. One chapter is devoted to Lorentz’s wife Aletta, a woman in her own right, whose progressive feminist ideas were of considerable influence on those of her husband. Two separate chapters focus on his most important scientific achievements, in terms accessible to a general audience.