Read it through once

“When Browning wrote this poem, he knew that the mastership or pupilship of Fra Lippo to Masaccio (called ‘Guidi’ in the poem), and vice versa, was a moot point; but in making Fra Lippi the master, he followed the best authority he had access to, the last edition of Vasari, as he stated in a Letter to the ‘Pall Mall’ at the time, in answer to M. Etienne {a writer in the ‘Revue des deux Mondes’.} Since then, he finds that the latest enquirer into the subject, Morelli, believes the fact is the other way, and that Fra Lippo was the pupil.”--B. Soc. Papers, Pt. II, p. 160.