Certain minor peculiarities of language are used unconsciously by poets  If such peculiarities appear in the works of more than one poet, they are likely to reflect the language in common use during the poets' time  However, if they appear in the work of only one poet, they are likely to be personal idiosyncrasies
As such, they can provide a kind of fingerprint that allows scholars, by comparing a poem of previously unknown authorship to the work of a particular known poet, to identify the poem as the work of that poet
A peculiarity of language in a poem of unknown authorship could be evidence either that the poem was written by the one author known to use that peculiarity or that the peculiarity was not unique to that author.