The Earth is the cradle of humanity, but mankind cannot stay in the cradle forever. Konstantin Tsiolkovsky
Konstantin Eduardovich Tsiolkovsky (Russian: Константи́н Эдуа́рдович Циолко́вский; 17 September [O.S. 5 September] 1857 – 19 September 1935) was a Russian and Soviet rocket scientist who pioneered astronautic theory. Along with the Frenchman Robert Esnault-Pelterie, the Germans Hermann Oberth and Fritz von Opel, and the American Robert H. Goddard, he is one of the founding fathers of modern rocketry and astronautics. His works later inspired leading Soviet rocket-engineersSergei Korolev and Valentin Glushko, who contributed to the success of the Soviet space program.
Witty observation, disparaging remark, question for A.A., well this is your chance.