If we had a hydrogen economy worldwide, every nation on earth could create its own energy source to support its economy, and the threat of war over diminishing resources would just evaporate. ↗
Then about 1951 I began writing again, painfully, a novel I called in the beginning A Life Sentence on Earth, but which developed into The Tree of Man. ↗
But the revolutions and changes which are responsible for the present state of the earth are not limited to the upsetting of the ancient strata and to the ebbing of the sea after the formations of new layers. ↗
Secondly, the nature of the revolutions which have altered the surface of the earth must have had a more decisive effect on the terrestrial quadrupeds than on the marine animals. ↗