I managed to attend one session of the Yeats Summer School in Sligo and heard two interesting lectures on early Yeats.
Peter McDonald of Oxford University lectured on Yeats's Juvenilia. He started by asking Where/When does a poet begin? Some very early and he mentioned Wordsworth, Tennyson, Shelley and Pope as prolific teenage poets. Others write a lot in their youth which later is rightly forgotten. This is what is usually classed as juvenilia.
He wondered why there wasn't a similar name for poetry produced at the other end and did say that in Walter Savage Landor's 14 volume collected works there was a section at the end called senilia. Leigh Hunt called his debut collection Juvenilia with the subtitle a Collection of Poems Written between the ages of Twelve and Sixteen.
There is no juvenilia section in Yeats just some carefully winnowed works of youth in the early books.
A poet starts with another poet, McDonald said, meaning that poets write under others' influences until they find their own voice. And he looked at the poets who influenced Yeats from the evidence in his first published poem The Island of Statues and early versions of Oisin. Spencer, Shelley, Tennyson are the great influences at this time.
The lecture ended with the admission that most of this early work by Yeats is not of great quality and of interest only to the scholar and that there is no answer to the question posed at the start.
Yeats' first play, Love and Death, 1885, previously unpublished has just been published by Boston College on the internet and a reading was given at the Summer School.
Peter McDonald is a poet himself and his recent volume Torchlight is reviewed here.
I didn't have time to attend Peter's poetry reading or the Yeats play reading. History called. Note to self : After the book is finished attend at least one week of the Yeats Summer School.