Isaiah mentions four ways of threshing: the staff or flail, which was used for the smaller seeds; the drag, formed of strong planks, the lower part of which was made rough with stones or iron; the cart, having wheels furnished with iron edges or teeth; and the feet of oxen driven over the corn when laid on the floor. The grain was winnowed by being thrown against the wind with a shovel. The traditions of ancient times ascribe many of its arts to the visions and instructions of superior beings. Among these stands forth with special prominence the legend of “the fire-bringing Prometheus,” as depicted by Æschylus with extraordinary power. He appears chained to the mountains of Caucasus; and why is he thus doomed to suffering? For disobedience to the power that rules the world, in bestowing fire on the human race. “Laboring for the people,” and intent on giving them “all-working fire,” it is to restrain him from “his man-loving turn of mind,” that he is cast forth from society, and that the far-distant and barren rock is his inexorable destiny. How man received the gift of fire we have no means of knowing. It is a Moslem fable that the angel Gabriel brought it to our first parents. Poetry says that the winds blew through the grove, that two trees became ignited from continued attrition, and that Adam beholding the lighted copse fled, turned back, caught the glow of the flame, and then tried various means to obtain it. Again, it tells us that a flint-shaft, aimed at a beast, ground against a rock, and elicited sparks of fire, which led Adam to rub stones together over dry leaves, while Eve gently cherished the kindling flame. More than one ancient people ascribe it to the rubbing of two pieces of wood together, a practice still adopted among barbarous tribes. But however this might be, fire must have been possessed in earliest times for the preparation of human food, as well as for the practice of those arts which are ascribable to the fatherhood of Tubal-Cain.