Ernst Mach, in an exclamation after a lecture by Ludwig Boltzmann, as quoted in notes by Boltzmann in Ernst Mach; His Work, Life, and Influence (1972), by John T. Blackmore, Ch. 14 : Mach vs. Boltzmann, Planck, Stumpf, and Külpe, p. 206https://en.wikiquote.org/wiki/Atom