§2. Principles and Method. The determination of the leading Athanasian dates depends mainly on the value to be assigned to the primary sources, §1 (1). Reserving the fuller discussion of these texts for the Introduction to the Letters (pp. 495 sq ., 500 sq .), it will suffice to state here what seem to be the results of an investigation of their value. (1) The Historia Acephala and Festal Index are independent of each other (cf. Sievers, p. 95, misunderstood, I think, by Mr. Gwatkin, p. 221). (2) They both belong to the generation after the death of Athanasius, the H. A. being apparently the earlier. (3) The data as to which they agree must, therefore, come from a source prior to either, i.e., contemporary with Athanasius. (4) In several important particulars they are confirmed by our secondary Egyptian sources, such as the Letter of Ammon and Life of Pachomius . (5) They verify most of the best results arrived at independently of them (of this below), and (6) In no case do they agree in fixing a date which can be proved to be wrong, or which there are sound reasons for distrusting. On these grounds I have classed the Historia and Index as primary sources, and maintain that the dates as to which the two documents agree must be accepted as certain. This principle at once brings the doubtful points in the chronology within very moderate limits. The general chronological table, in which the dates fixed by the agreement of these sources are printed in black type, will make this plain enough. It remains to shew that the principle adopted works out well in detail, or in other words, that the old Alexandrian chronology, transmitted to us through the twofold channel of the Historia and the Index , harmonises the apparent discrepancies, and solves the difficulties, of the chronological statements of Athanasius, and tallies with the most trustworthy information derived from other sources. In some cases it has been found desirable to discuss points of chronology where they occur in the Life of Athanasius; what will be attempted here is to complete what is there passed over without thorough discussion, in justification of the scheme adopted in our general chronological table.