This thesis is principally a chronological study of Tristan's lyrical poetry - a facet of his work dealt with only very fleetingly in Bernardin's thesis of 1395 - in the light of the revival of interest in, and re-evaluation of French poetry of the period. We have had, however, to include also a certain amount of Biographical material: firstly, "because a knowledge of the circumstances of the poet's life is essential to the dating and understanding of his works; secondly, Because we disagree on certain points with Bernardin's findings; and lastly Because Professor Adam had sought, in his 1935 thesis on Theophile, to demolish our predecessor's account of the first twenty years of Tristan's life.