Thought-Culture; or, Practical Mental Training

...and his young from the fury of the storm—first by using caves and afterwards by building simple original: "rude" houses. These were built in hard-to-reach original: "inaccessible" places and could only be reached using crude ladders, bridges, or climbing poles. He built doors for his dwellings original: "habitations" to protect himself from the attacks of these wild enemies, and he piled original: "heaped" stones at the mouths of his caves to keep them out.

He placed great boulders on cliffs so that he could topple them down onto any approaching enemies original: "foe". He learned to hurl rocks with a steady original: "sure" aim using his strong arm. He copied the floating log and built his first simple original: "rude" rafts, later developing original: "evolved" the hollowed-out canoe. He used animal skins to keep himself warm and their tendons for his bowstrings. He learned the advantages of cooperation and combined effort, and in doing so, formed the first foundations original: "rudiments" of society and social life. Finally—humanity's first great discovery—he found the art of making fire.

As one writer has said:

"For several hundred years, on the level of self-awareness original: "general plane of self-consciousness", a rise original: "ascent" has been made. To the human eye, this progress seems gradual, but from the perspective of cosmic evolution, it has been rapid. This occurred in a race that was large-brained, walked upright, and was social original: "gregarious"..."