they can and what they cannot do. The discussion
The Work on the Councils and the Churches
contains repeated references to his sources of knowledge.
They are Eusebius' Ecc1esiastical History, which he used in Rufinus' Latin translation, with that author's supplements; Cassiodorus' Historia tripartita, which consisted of translated excerpts from the histories of Theodoret, Socrates, and Sozomen; and the Canon Law. To these were add ed the then newly published, two-volume work of Peter Crabbe, issued in 1538 under the title Concilia omnia. It was the most comprehensive collection of material bearing upon the councils to which he had access, and he quotes it frequently. He also cites, though with much criticism, Platina's Lives of the Pope(Historia de vitis pontificum, written between 1471 and 1481).
The work falls into three parts. Part 1 argues the thesis that the Church cannot be reformed according to the councils and the fathers.
Part 2 discusses the functions of councils, what they can and what they cannot do. The discussion takes a broad scope. Luther takes up the first four ecumenical councils, — Nicaea (325), Constanti nople (381), Ephesus (431), and Chalcedon (451), — and the Council of Jerusalem in apostolic days. He examines the records of their proceedings with a view to determining what they actually did, and what of their acts had purely temporary and what