Full Idea
Whatever someone has himself substantially made is his own undisputed property.
Gist of Idea
If someone has largely made something, then they own it
Source
Immanuel Kant (Metaphysics of Morals I: Doctrine of Right [1797], §55)
Book Reference
Kant,Immanuel: 'Political Writings', ed/tr. Reiss,Hans [CUP 1996], p.166
A Reaction
To this extent Kant offers clear agreement with Locke about a self-evident property right. Ownership of land is the controversial bit.