Full Idea
One strays from the purpose of definitions if one confines oneself to a formal account and simply discards the material element.
Gist of Idea
The material element may be essential to a definition
Source
Aristotle (Metaphysics [c.324 BCE], 1036b20)
Book Reference
Aristotle: 'Metaphysics', ed/tr. Lawson-Tancred,Hugh [Penguin 1998], p.208