"H.A. Lorentz, The Einstein Theory of Relativity: A Concise Statement"

“Einstein's theory has the very highest degree of æsthetic merit: every lover of the beautiful must wish it to be true. It gives a vast unified survey of the operations of nature, with a technical simplicity in the critical assumptions which makes the wealth of deductions astonishing. It is a case of an advance arrived at by pure theory: the whole effect of Einstein's work is to make physics more philosophical , and to restore some of that intellectual unity which belonged to the great scientific systems of the seventeenth and eighteenth centuries, but which was lost through increasing specialization and the overwhelming mass of detailed knowledge. In some ways our age is not a good one to live in, but for those who are interested in physics there are great compensations.”

“H.A. Lorentz, The Theory of Electrons and Its Applications to the Phenomena of Light and Radiant Heat”

“Let there be in every material particle several material points charged with electricity, of which, however, only one be movable, and have the charge e and the mass μ.”

“Theory of relativity”