In a letter written in early 1428, a merchant told of having seen the design for a much-discussed new coin called the "rose noble. " The Royal Theatre Company includes the play on a list of those performed in 1480. The rose noble was neither minted nor circulated after 1468. Although Henry VI was deposed in 1461, he was briefly restored to the throne in 1470.
The play Mankind must have been written between 1431 and 1471. It cannot have been written before 1431, for in that year the rose noble, a coin mentioned in the play, was first circulated. The play cannot have been written after 13471, since in that year King Henry VI died, and he is mentioned as a living monarch in the play' s dedication.
The argument would be most seriously weakened if which one of the following were discovered?