Note 48 — Chapter I · PREAMBLE: ON THE ORIGIN OF WEAPONS.

Specus erant pro domibus. Caverns appear to be divisible into three classes: dwelling-places—including refuges, where, as Prometheus says (i. 452), ‘Men lived like little ants beneath the ground in the gloomy recesses of grots’—storehouses, and sepulchres. All were in Lyell’s third phase. The first was when the rock began to form the channel by dissolution; the second, when a regular river flowed; and the third, when earth and air, instead of water, filled the bed.