The bad Quartos are useful, however, because they demonstrate theatre practice - for example, the extent in which plays were cut and revised. This is of course part of the action in Hamlet. The Prince turns The Murder of Gonzago into The Mousetrap, a “play within a play”, by inserting 12-16 lines of his own composing.
WHAT DO YOU CALL THE PLAY? THE MOUSETRAP.… THIS PLAY IS THE IMAGE OF A MURDER DONE IN VIENNA.
The other eight Quartos we have of Shakespearean plays are “good” Quartos, which means that they were authorized by Shakespeare and the players: Titus Andronicus, Richard II, Richard III, Henry IV Parts One and Two, Much Ado About Nothing, A Midsummer Night’s Dream, and The Merchant of Venice.
The Chamberlain’s Men now left the Rose and built the Globe Theatre. It opened with Julius Caesar in 1599. Shakespeare followed this with Hamlet, and then Troilus and Cressida (which was performed neither then, nor for almost three centuries). Nevertheless, with Hamlet, Shakespeare had moved into another realm. Gabriel Harvey said in about 1601 …
THE YOUNGER SORT TAKES MUCH DELIGHT IN SHAKESPEARE VENUS, & ADONIS: BUT HIS LUCRECE, & HIS TRAGEDIE OF HAMLET, PRINCE OF DENMARKE, HAVE IT IN THEM, TO PLEASE THE WISER SORT.