I think you will recognise that it was necessary to get rid of Brunetto for two reasons . The first is that the visionary figure has now become somewhat more definite and will no doubt be identified by some readers with Yeats though I do not mean anything so precise as that . However , I do not wish to take the responsibility of putting Yeats or anybody else into Hell and I do not want to impute to him the particular vice which took Brunetto there . Secondly , although the reference to that Canto is intended to be explicit , I wish the effect of the whole to be Purgatorial which is more appropriate . That brings us to the reference to swimming in fire which you will remember at the end of Purgatorio 26 where the poets are found .