The two strands of the narrative converge when the connections between them (such as the implications of geology for the age of the earth and the origin of species) intensify.

ECONOMIST: History of science: Time's arrow | The

Like the Jews, the Muslims came to see the Rock as a meeting point between God and Man, the centre of the earth, the origin of all fertility.

ECONOMIST: New fiction from the Middle East

He landed, camped there, left and returned, studied, researched and conceived his earth-shaking theory of evolution, On the Origin of Species, in 1859.

FORBES: Connect

And the nuclear-winter hypothesis (that the smoke from fires caused by a global nuclear war would blot out the sun's rays and thus cool the earth catastrophically) owes its origin, at least in part, to observations of a planet-wide dust storm on Mars.

ECONOMIST: Comparative meteorology