Four kinds of causation distinguished by Aristotle. If we think of an example of something that is produced by an agent, such as a statue, then the material cause is the substance or material that constitutes the statue; the formal cause is the pattern or blueprint determining the form of the result; the efficient cause is the agency producing the result; and the final cause is that for the sake of which the result is produced, i.e. the end towards which the production is directed. Whilst the notions may be clear enough in such a case, their wider applicability is much more doubtful. There are clearly events (e.g. a lightning flash) that we think of as caused, yet which are not made of material, not made according to a blueprint, not the result of agency (at least where that is intelligent agency), and apparently purposeless. Aristotle’s generally teleological approach to nature almost certainly led him to see the categories as more widely applicable than we do.