The paragraph is followed by an incomplete phrase or sentence which summarizes the main idea of the paragraph. Choose the missing words of the phrase or sentence.

Since their first appearance on earth, men have gathered in formation and have attempted to pass useful ideas to other men.The carving of word-pictures on the walls of ancient caves as well as hieroglyphics on stone tablets represen some of men's earliest efforts to convey information. Scenes of hunting, maps of battles, and the stories of heroes were put down for all to see.

Men have gathered information and （） ideas to other men.