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 poet's use of some peculiarities of language might have been unconscious in some poems and conscious in other poems, and the two uses would be indistinguishable to scholars at a later date.