The Earth is the cradle of Humanity. But one doesn't always live in the cradle.

Man must at all costs overcome the Earth's gravity and have, in reserve, the space at least of the Solar System.

For me, a rocket is only a means--only a method of reaching the depths of space--and not an end in itself... There's no doubt that it's very important to have rocket ships since they will help mankind to settle elsewhere in the universe. But what I'm working for is this resettling... The whole idea is to move away from the Earth to settlements in space.

Man must at all costs overcome the Earth's gravity and have, in reserve, the space at least of the Solar System. All kinds of danger wait for him on the Earth. . . . We have said a great deal about the advantages of migration into space, but not all can be said or even imagined.

The Earth is the cradle of Humanity. But one doesn't always live in the cradle.

All our knowledge - past, present, and future - is nothing compared to what we will never know.

A planet is the cradle of mind, but one cannot live in a cradle forever.