Chaucer, by reason of his intimate acquaintance with both the poetry and prose-fiction of Boccaccio, had the opportunity to choose between these two mediums of short-story narration; and he chose the former. He was as familiar with Boccaccio's poetic method, as exemplified in the _Teseide_, as with his prose, as exemplified at much greater length in the _Decameron_, for he borrowed from them both. Yet in only two instances in the _Canterbury Tales_ does he relapse into prose. The _Teseide_ in Chaucer's hands, retaining its poetic medium, is converted into the _Knight's Tale_; while the _Reeve's Tale_, the _Franklin's_, and the _Shipman's_, each borrowed from the prose version of the _Decameron_, are given by him a poetic setting. This preference for poetry over prose as a medium for short-story narration cannot have been accidental or unreasoned on his part; nor can it be altogether accounted for by the explanation that "he was by nature a poet," for he _did_ experiment with the prose medium to the extent of using it twice. He had the brilliant and innovating precedent of the _Decameron_, and yet, while adopting some of its materials, he abandoned its medium. He was given the opportunity of ante-dating the introduction of technique into the English prose short-story by four hundred and fifty years, and he disregarded it almost cavalierly. How is such wilful neglect to be accounted for? Only by his instinctive feeling that the technique, which Boccaccio had applied in the _Decameron_, belonged by right to the realm of poetry, had been learned in the practising of the poetic art, and could arrive at its highest level of achievement only in that medium.