Full Idea
We should not only be grateful to those in whose opinions we at all share but also to those who have gone astray, for even the latter have contributed something.
Gist of Idea
Even people who go astray in their opinions have contributed something useful
Source
Aristotle (Metaphysics [c.324 BCE], 0993b12)
Book Reference
Aristotle: 'Metaphysics', ed/tr. Lawson-Tancred,Hugh [Penguin 1998], p.43
A Reaction
Yes, but what have they contributed? Have they revealed lines of reasoning, or are they just a terrible warning?