A patent is, ultimately, a negative entity. Before a patent is granted, anybody can make certain objects or perform certain techniques. After it's filed, the patent owner's rights remain unchanged, but everybody else is restricted from doing those things.

Humans have an intrinsic idea of "property" that the legal idea is built upon. A two-year-old child understands the idea of "mine". People still own things when government is not present, they just have a harder time enforcing that ownership.

Patents, on the other hand, are an entirely governmental construct.