The Earth is the cradle of Humanity. But one doesn’t always live in the cradle. — Konstantin Tsiolkovsky
First, inevitably, the idea, the fantasy, the fairy tale. Then, scientific calculation. — Konstantin Tsiolkovsky
The earth is the cradle of humanity, but mankind cannot stay in the cradle forever. — Konstantin Tsiolkovsky
Man must at all costs overcome the earth’s gravity and have, in reserve, the space at least of the solar system. — Konstantin Tsiolkovsky
