From its earliest practice, craft knowledge has entailed knowledge of the "ways" of one's materials--that is, knowledge of their nature, acquired through disciplined perception. At the beginning of the western tradition, Sophia (wisdom) meant skill for Homer; the technical skill of a carpenter, for example. Through pragmatic engagement, the carpenter learns the different species of wood, then fitness for such needs as load bearing and water holding, their dimensional stability with changes in the weather, and their varying resistance to rot and insects. The carpenter also gains a knowledge of universals, such as the right angle, the plumb, and the level, which are indispensable for sound construction. It is in the crafts that nature first becomes a thematic object for study, and that study is grounded by a regard for human activity.