On September 26, 1905 (received June 30), Albert Einstein published his annus mirabilis paper on what is now called special relativity. Einstein's paper includes a fundamental description of the kinematics of the rigid body, and it did not require an absolutely stationary space, such as the aether. Einstein identified two fundamental principles, the principle of relativity and the principle of the constancy of light (light principle), which served as the axiomatic basis of his theory. To better understand Einstein's step, a summary of the situation before 1905, as it was described above, shall be given (it must be remarked that Einstein was familiar with the 1895 theory of Lorentz, and Science and Hypothesis by Poincaré, but possibly not their papers of 1904–1905):