Tucked into the front matter of an obscure Vermont horse-training manual from 1866 is one of the earliest examples of what we would now recognize as a restrictive end-user license agreement — the kind of legal fine print we now associate with software rather than farriery.

Directly above the copyright notice, York & Williams printed this warning:

TO PURCHASERS. Persons buying this work have every right of using, but no right of teaching, or transferring to others, the book or its contents. By so doing they will lay themselves liable to prosecution.

Read that again. The authors are claiming that when you buy their book, you receive only the right to use the knowledge inside — not to teach it, and not even to hand the physical book to someone else. This is essentially a proto-EULA, printed almost a century before software makers began attaching similar terms to shrink-wrapped floppy disks.

The book itself was a horse-handling manual by two itinerant trainers who traveled the United States and Canada demonstrating their system for gentling "wild and vicious horses." Their livelihood depended on paid demonstrations — so their business model was threatened by the very act of publishing. If a farmer read the book and then taught his neighbors, York & Williams lost customers. Their solution was to invent, on their own authority, a private restriction that copyright law did not actually grant them.

Was it enforceable? Almost certainly not, even in 1866. Copyright has always protected the specific expression of ideas, never the ideas themselves. You cannot copyright a horse-taming technique any more than you can copyright a recipe or a mathematical proof. And the notion that a buyer cannot resell or give away a book they legally purchased was formally demolished by the U.S. Supreme Court in 1908 in Bobbs-Merrill Co. v. Straus, which established the first-sale doctrine. But in 1866 — before that ruling — an ambitious warning printed in bold type might have been enough to deter most readers.

The modern echo. Anyone who has clicked "I Agree" without reading has encountered the intellectual descendant of this 1866 warning: the claim that your purchase grants a limited license rather than ownership, that you may use but not share, that violation invites "prosecution." When John Deere argues you don't really own the tractor you paid for, or when a textbook publisher forbids you from reselling your used copy, they are making the same argument York & Williams made about horse-taming secrets — just with better lawyers.

What's remarkable is not the greed but the earliness. A century and a half before software licensing, two Vermont horse trainers had already intuited the entire logic of the modern IP restriction: sell the artifact, retain control of the knowledge.