We know he uses both the Catena aurea of Thomas Aquinas and John Gerson's Monotessaron as his "basic tools" for composing De Tristitia.
As Miller observes, the Monotessaron presents More with three points of discussion on this verse--the selection of Peter, John, and James; the sadness and fear of Christ; and Christ's command to pray with him--but More is "primarily interested in the second point, to which he devotes more than fifteen times as much space as to the other two points combined." (48) More's cancelled passages from the Valencia manuscript show how he revises, striking his treatment of points one and three so he may elaborate upon Christ's sadness and fear.
The analyses offered here are noteworthy because they undoubtedly open windows for further study of such little known works as the Monotessaron, the Treatise on songs, and the Compilation on the Magnificat.
Our attention is drawn to the rubrics of the Monotessaron, which are organized in a table of contents with corresponding Gospel references, and to the mnemonic verse to aid the memorization of its contents; Gerson himself most likely created these himself since he accurately described them in a letter to a Celestine monk.