Aristotle's Theory of the Efficient Cause

Aristotle says there are four types of causes: efficient, final, material and formal. The form of a computer is basically whatever allows it to achieve its purpose. To give a more aristitelean example than the computer, a carpenter might impose the form of a table on some wood in order to have something to eat off. It may not seem that important to point but philosophers will wrestle with this implication of aristotle's theory for many centuries.