"Copyright" was unheard of. Bards went from place to place, singing the songs they made up (and the ones they heard from other bards). A given town or castle would see an outside entertainer perhaps once or twice a year, so it didn't really matter if another bard copied your song -- or put his own spin on it (a "derivative work").
Similarly for patents. THere was only one way to keep hold of a piece of IP: keep it a secret and never tell anybody except close family members and other people you trust completely. That happened with forceps for breach births: one obstetrician invented it, and told nobody except his family. It might have been lost except that one person blabbed the secret. And without modern IP law, there was nothing to keep everybody else from making and using them.
And of course until Gutenberg, the only way to make copies of something was for somebody to take a quill and write it -- by hand -- on parchment, vellum, or papyrus. Copying a documents was expensive, especially since it could only be done by the (relatively small) literate class.
Then came the printing press, and you could make lots of copies -- once you did the work of setting the type. And it became possible to make *money* off those copies, so it an exclusive right to copy became a good thing for those who created a story, poem, essay, etching, etc.
Then came the mimeograph (stencil duplicator) and spirit duplicator (aka Ditto, but Ditto® is a brand name). And anybody with a typewriter and a few $100 to spend on a duplicator could make copies, for not much more than the cost of the paper to print it on.
And then came the Xerox and other photocopiers, and copies became cheaper yet. And enforcing copyright became a problem. When anybody can make a copy for not much money, the temptation to just copy what you need instead of paying for the whole book started cutting into publishers' profits. And the advent of the tape recorder -- and especially the portable cassette recorder -- created the same problem for music publishers.
Now this trend is reaching its logical conclusion: once something is recorded in digital form, the cost of making copies is essentially $0. It's just disk space (and if your disk gets full, you buy another 500GB for $100 (or less). In the past, I've found an MP3 takes about 1MB per minute of music, so that works out to about about $.01 per *hour*. And almost everybody has a computer of some sort these days. If you don't, the public library does -- and if the library won't let you burn DVDs, there's always a cyber cafe.
Moving your music (or movie) to an CD or DVD for portability is a little more expensive, but CD-Rs are a dime or less, while DVD-Rs are about a quarter. The "jewel box" costs more than the CD/DVD inside it.
In short, the advance of technology made copyright desirable, but it may now make it impractical. Unless...
If Moore's Law continues to hold, it is possible that we will develop systems that can actually recognize a copyright work, in the same way that a human being can -- even if somebody has edited it into a new form, or changed it to cover up a watermark. What then? Will Congress try to require that file-sharing sites and software deploy such a system to protect copyright? Would such a requirement be effective? Would it be acceptable to people?
I don't know. I'm not a prophet (though I think I might have become one if I'd dared).