Full Idea
It is not right to seek a definition for everything - for some things an overview is to be had by analogy.
Gist of Idea
Some things cannot be defined, and only an analogy can be given
Source
Aristotle (Metaphysics [c.324 BCE], 1048a33)
Book Reference
Aristotle: 'Metaphysics', ed/tr. Lawson-Tancred,Hugh [Penguin 1998], p.267
A Reaction
This is what David Lewis called the 'way of example' in defining what is meant by 'abstract objects'.
Related Idea
Idea 8938 The Way of Example compares donkeys and numbers, but what is the difference, and what are numbers? [Lewis]