 In thinking about the four causes, we have come to understand that Aristotle offers a teleological explanation of the production of a bronze statue; that is to say, an explanation that makes a reference to the telos or end of the process. Moreover, a teleological explanation of the type sketched above does not crucially depend upon the application of psychological concepts such as desires, beliefs and intentions. This is important because artistic production provides Aristotle with a teleological model for the study of natural processes, whose explanation does not involve beliefs, desires, intentions or anything of this sort. Some have objected that Aristotle explains natural process on the basis of an inappropriately psychological teleological model; that is to say, a teleological model that involves a purposive agent who is somehow sensitive to the end. This objection can be met if the artistic model is understood in non-psychological terms. In other words, Aristotle does not psychologize nature because his study of the natural world is based on a teleological model that is consciously free from psychological factors. (For further information on the role that artistic production plays in developing an explanatory model for the study of nature, see Broadie 1987, pp. 35–50.)