Above it, however, and a very great improvement upon it, is the agricultural stage, where the main source of the food supply is the harvests. You observe, at once, that that means a sedentary life. When a man sows corn, he must wait thereabout and tend it and till it and finally reap it and store it and thrash it and then preserve the grain and build granaries for it; and it involves, in fact, the remaining in one place all the whole year; and then the regularity of that life led very distinctly to making men regular, generally, in their habits. They wanted to defend their homes—defend these grain fields of theirs, or starvation would result; therefore, they built towers and strong-walled cities; and they took great care in the selection of the best men among them to do the fighting, while others looked after the crop. We find that agriculture began at a very, very early period in both continents. In our own continent we cannot tell when agriculture was first in use—the main crop being the maize, or Indian corn. It was raised by the more advanced tribes from the extreme north, where its profitable culture invited, to the extreme south, from about the northern line of Wisconsin in North America to the latitude of southern Chile in South—extending, therefore, over some seven to eight thousand miles of linear distance. In the old world (going back to the time of the lake dwellers) we know they had barley, rye and a species of millet; and later on they were introduced to oats and wheat and a variety of others. Rice was of the very earliest of our cereals, in the extreme east of the old world. Wherever we find a very ancient civilization we also find that it is intimately connected with some important cereal, and it has been said that all you have to do is to study botany—the history of botany—and you will find the history of human culture; and much there is that could be said for that.