Nevertheless, according to the tradition of writing history at the time, he felt obliged to relate what he read (or heard) without passing judgment as to its truth or untruth. One of the problems of modern scholarship is to ascertain where in the work the line is to be drawn between legendary and historical. One view has been that buildings, inscriptions, monuments and libraries prior to the sack of Rome in 387 BC by the Gauls under Brennus were destroyed by that sack and were scarcely available to Livy and his sources. This view originates from Livy himself, who notes this fact. A layer of ash over the lowest pavement of the comitium believed to date from that time seemed to confirm a citywide destruction.