Throughout history, knives have been essential for survival, as well as for providing food and shelter. From its earliest form, the knife developed out of necessity, and its evolution may be traced through paths of technology. During the Stone Age, knives were made of flint, which could easily be scaled to shape, and then could be re-scaled to produce a new edge. Later, flint knives were ground to the desired shape. Much later in history, man began to make knives from copper, bronze, and finally, from the products of iron as we know them today.