"Property is Theft"
Pierre-Joseph Proudhon from
What is Property? Or, an Inquiry into the Principle of Right and of Government.
"Good Artists Copy; Great Artists Steal." - Steve Jobs
The same thing, clarified:
"One of the surest of tests is the way in which a poet borrows. Immature poets imitate; mature poets steal; bad poets deface what they take, and good poets make it into something better, or at least something different. The good poet welds his theft into a whole of feeling which is unique, utterly different from that from which it was torn; the bad poet throws it into something which has no cohesion. A good poet will usually borrow from authors remote in time, or alien in language, or diverse in interest."
TS Eliot, circa 1920
More succinctly, from 1967:
Igor Stravinsky said to me of his Three Songs by William Shakespeare, in which he epitomized his discovery of Webern’s music: “A good composer does not imitate; he steals.”
A better example:
“immature artists copy, great artists steal.” Knowing what and when to steal is very much a part of the designer’s self-education.
Faulkner, about 1974
One aspect of property is that it must be defined, measured and assigned.
If you've not done this with what you claim is yours, you've got no hope of doing anything other than paying lawyers to slowly, painfully, and very expensively demonstrate this reality to you. At your expense.
And they'll be very happy to do that.