Full Idea
The capacity to set oneself an end - any end whatsoever - is what characterises humanity (as distinguished from animality).
Gist of Idea
Humans are distinguished from animals by their capacity to set themselves any sort of end
Source
Immanuel Kant (Metaphysics of Morals II:Doctrine of Virtue [1797], 392 Intro VIII)
Book Reference
Kant,Immanuel: 'The Metaphysics of Morals', ed/tr. Gregor,Mary [CUP 1991], p.195
A Reaction
This appears to exclude animals which hunt, or build nests - but we have now hugely closed the gap between humans and other animals. I like this, because it chimes in with Sandel's Idea 21045.
Related Idea
Idea 21045 Teleological thinking is essential for social and political issues [Sandel]