That Roman association between theft of intellectual property is embedded in the word plagiarism. Etymologically, plagiary comes from the Latin plagirius, kidnapper, and plagiarist, from plagium, kidnapping. Latin plagium is from plaga. There's a metaphor there, in that for writers, quite often their books are (metaphorically speaking) their children. To steal their words (or images or sounds) is thus a form of kidnapping.

Kidnapping is certainly an interesting way to look at intellectual property theft and copyright violation. It reminds me of an c. 6th century early Irish legend about Saint Columcille (also known as St. Columba or Colum Cille or Colmcille), and King Diarmaid. Colum, a monk and founder of the monastery on Iona, was in the habit of traveling all over Ireland and borrowing books from other monasteries in order to copy them. Not everyone agreed with this practice. Saint Finian of Clonard in particular objected strenuously about Columcille (once his student) copying a psalter, a book of psalms, that belonged to Finian. Finian complained to the High King of Ireland, Diarmaid, and requested a formal judgement.

The early Irish law code is contained in the body of knowledge called the Brehon Laws. Among other basic concerns covered by the Brehon Laws are the problems faced by a largely agrarian society when cows, or pigs, or bees go wandering into someone else's land. The law stipulates that a calf, no matter where it is found, belongs to its mother, wherever she might be.

Apparently, Diarmaid had that law in mind when he delivered his judgement:

"To every cow its calf, so to every book its copy."

Diarmaid's judgement is the earliest known instance of copyright law. To Diarmaid, as to the ancient Romans, copying a book, plagiarizing was an act of kidnapping. Unfortunately, in 555, according the the Irish history chronicle known as the Annals of the Four Masters, Diarmaid's judgement led was one of the causes of the battle of Cul Dreimhne (Anglicized as Cooldrevne), which ended in the death of 3000, it was said, and ultimately, to Columcille's self-exile to the island of Iona. In 563, Columcille, and twelve companions crossed the Irish Sea in a coracle, where he founded one of the most important monasteries in the world.