Origin of word masterpiece?

Federico Zuccari, Two Painter's Apprentices, 1609.

Definition

"a work or performance of a master, a piece of work of surpassing excellence," c. 1600, from master (n.) + piece (n.1).

Etymology 

Loan word from the Dutch meesterstuk and its German cognate meisterstück to the culmination of the apprenticeship process. This was like the  final exam piece sometimes used to judge students on art or music courses. 

Early Usage 

That described  A goldsmith, for example, might present a piece of jewellery for inspection by members of the the guild. Surpassing excellence  here was based more on meeting a standard rather than creating a new one to which others might aspire.

If accepted, this would complete an apprenticeship (typically lasting seven years) and be the "work by which a craftsman attains the rank of master". 

Team work

Apprenticeships within the guild system were crucial to the expansion of the middle classes. Though we associate the word with individual exceptionalism the words was initially used in its pre-Romantic sense - as the outcome of a team effort. 

As Daniel Swift argues in "The Making of William Shakespeare" it is important to remember that audiences thought of plays as being by a company of players rather than an individual writer.

Modern Usage

Bob Dylan's When I Paint My Masterpiece expresses the modern sense of the term - with a masterpiece being both exceptional and a benchmark of progress: 

That's what the song tries to say.... even if you do paint your masterpiece, what will you do then? Well, obviously you have to paint another masterpiece".[2]