In this stage of affairs there appeared to us like a wonderful ray of light the beautiful hypothesis of energy elements which was first expounded by Planck and then extended by Einstein and Nernst, and others to many phenomena. It has opened for us unexpected vistas, even those, who consider it with a certain suspicion, must admit its importance and fruitfulness.

In an early memoir, which became famous, Lorentz applied for the first time considerations relating to discrete molecules to electric propagation in material bodies, and incidentally arrived at a rational reflection-equivalent for each substance independent of its density. In 1884 he began to study the effect which magnetization exerts on the polarization of reflected light. His "Théorie Electromagnétique de Maxwell et son application auz Corps Mouvants" Ⓣ and his "Versuch einer Theorie der Elektrischen und Optischen Erscheinungen in bewegten Körpern" Ⓣ were published in 1892 and 1895 respectively. They embodied the first systematic appearance of the electrodynamic principle of relativity, and in 1920 he brought out "The Einstein Theory of Relativity: A Concise Statement". In 1909 he published his "Theory of Electrons", based on a series of lectures at Columbia University, and in 1916 he published in French at Leipzig an account of statistical thermodynamic theories, based on lectures delivered at the Collège de France in 1912. An edition of his University lectures, entitled "Lessons on Theoretical Physics", began to appear, under his supervision, in 1919. He was also the author of a textbook of the differential and integral calculus; "Visible and Invisible Movements", 1901; and "Clerk Maxwell's Electromagnetic Theory", 1924.

... a man of remarkable intellectual powers ... . Although steeped in his own investigation of the moment, he always seemed to have in his immediate grasp its ramifications into every corner of the universe. ... The singular clearness of his writings provides a striking reflection of his wonderful powers in this respect. .... He possessed and successfully employed the mental vivacity which is necessary to follow the interplay of discussion, the insight which is required to extract those statements which illuminate the real difficulties, and the wisdom to lead the discussion among fruitful channels, and he did this so skilfully that the process was hardly perceptible.

The funeral took place at Haarlem at noon on Friday, 10 February. At the stroke of twelve the State telegraph and telephone services of Holland were suspended for three minutes as a revered tribute to the greatest man Holland has produced in our time. It was attended by many colleagues and distinguished physicists from foreign countries. The President, Sir Ernest Rutherford, represented the Royal Society and made an appreciative oration by the graveside.