The intent of this study is to research several aspects of Aristotle's views on definition. In performance of this, it follows out the bequeathal of Platonic Idealism in a thinker constitutionally averse to any sort of form that is static, mathematical, or even visual, in comparison to one that is functional and organic. This is detailed first in Aristotle's turn away from that form (and the essential expression of form in its definition) for which intelligibility is based on mathematical ratio or a formula of design. Material or quantitative considerations of form, even those allied to the proportions of visual shape, lack the essentiality of an organizing principle and the activity that unifies the form. In other words, the essence of form is located not in the artifact but in the artisan. Aristotle is not thereby left with a definition of mute unintelligibility, but in abandoning quantitative ratio he accedes to an hitherto unprojected ratio of forms to end, a teleological ratio that is best expressed in his definition of soul in the De Anima but which also appears in various biological and even political contexts. In his concerns over teleological form, there is called into question the traditional logos of the definition by means of genus and last difference just there where it seems best accommodated, namely, in the forms of living creatures. In working out these tendencies in Aristotle, there arises necessarily a confrontation with the genetic aspects of Aristotle's thought. These are placed into context with the traditional and recent views of chronology in Aristotle. However, the ultimate appeals can only be made, owing to the sparsity of evidence, to arguments internal to the texts. These are supplemented in turn by the views of the ancient Greek commentators who stood with the availability of texts lost to us and who benefited somewhat, without doubt, by a closer proximity in time to the Lyceum.
