Yeats saw himself as a romantic in the tradition of Shelley, Keats and Blake, but also in a sense which included a poetic tradition going back to Dante and Spenser, Prof George Bornstein of Michigan University told the Yeats Summer School.
Pointing out that Yeats was an editor of some of Blake's work, he said the Irish poet was particularly influenced by Blake's doctrine of "contraries". But he was also influenced by Blake's emphasis on the material features of the text. "Yeats noticed how the overall design included more than the mere text of the words, and that illustration and layout could profoundly affect reception.
"A painter's son and would-be painter in his youth, Yeats's environment sharpened his sensitivity to physical features of the book, as did not only his study of Blake but also his early devotion to William Morris. Young Yeats clearly longed for input into the bibliographic codes of his own poetry and sought to influence the choice of designer and format for the Poems collection of 1895.
"He got his chance after the turn of the century," Prof Bornstein continued. This was the foundation of the Emer, later Cuala, Press, by his sisters in 1903. His sister Elizabeth had trained with William Morris's partner, Emery Walker. The poems were laid out high on the page, echoing medieval book design, and the books were manufactured in Ireland using Irish materials, giving a nationalist inflection to their contents.
"In that way the physical appearance of the volumes matched Yeats's largest claim as a reviser of romanticism: to have fastened it to an Irish national landscape."
Prof Bornstein described how, when his books were being published by Macmillan, Yeats continued to have a major input into their design. When the Tower volume of his poems was published, he made sure that his favourite designer, Sturge Moore, got the commission for the cover, and sent him photographs of his home, the tower of Thoor Ballylee.
His accompanying letter said: "I like to think of that building as a permanent symbol of my work plainly visible to the passer-by. As you know, all my art theories depend upon just this - rooting of mythology in the earth."
Dr Rand Brandes, of LenoiRhyne College in North Carolina, said: "Even if Seamus Heaney had never written a line of poetry, his name would live on as one of the great critics of our age, and, I would add, great Yeats critics."
He was describing Heaney's life-long relationship with the work of Yeats. "Heaney has written more on Yeats and alludes to Yeats more often than any other of his critical subjects. Heaney's Yeats will in many ways be the Yeats of future readers."
He said that, despite the brilliance of his critical work, Heaney himself pointed out that he is not a trained scholar.
The poet has written: "I was taken aboard the university on the basis of the poetry and given a fool's pardon to write impressionistic essays . . . "
Dr Brandes said Heaney's impressionistic approach is personal, intuitive, emphatic and rooted in the poetic pleasure principle.
Heaney's language in writing about Yeats was also important. Dr Brandes pointed to the use of words like "ram-rodding, striking, reining, subduing, rioting, straddling, harnessing, controlling, combating, handling and mastering."
"This was Yeats as Jedi warrior, sword in hand battling the dark side of discourse and the divided self. To have Yeats's creative energy is one thing; to control it is an even greater thing."
Although generally a supporter of Yeats, he said Heaney took on his politics in a 1979 essay, "A Tale of Two Islands". But "despite the intensity of Heaney's attack on Yeats, one senses that Heaney is not comfortable in the Judas role".
Heaney has always been cognisant of the less attractive, more problematic, Yeats. But he wrote that it "seems unnecessarily perverse to sully Yeats's whole reputation because of a small, strident and dangerous group of poems".
In the end he paid tribute to Yeats as "the poet who lived the perfect life, wrote the perfect poem, and died the perfect death".
The Yeats Summer School continues until August 13th, when Prof Roy Foster will give the final lecture on the reconstruction of Yeats's politics.