They gave themselves especially to the study of Holy Scripture, and to the practice of devotional exercises.  In their study their great principle was to interpret the holy writings not by their own individual judgment, but on the lines laid down for them by the authority of ancient interpreters.  Of uninspired commentators they had the greatest respect for Origen, whose errors, however, they happily avoided.  From his exegetical writings they compiled a book of Extracts, which they published in twenty-seven books, to which they gave the name of Philocalia, i.e., what in modern language is called a Christology.  This is happily still extant, and is valuable as preserving for us many passages otherwise lost, or existing only in a Latin translation.  Gregory sent a copy of this work to his friend and subsequent companion at Constantinople, Theodore, Bishop of Tyana, as an Easter gift many years afterwards, and accompanied it with a letter, in which he speaks of the work as a memorial of himself and Basil, and as intended for an aid to scholars; and begs that his friend will give a proof of its usefulness, with the help of diligence and the Holy Spirit.  Socrates says that this careful study of Origen was of the greatest service to the two friends in their subsequent controversies with the Arians; for these heretics quoted him in support of their errors, but the two Fathers were enabled to confute them readily, by shewing that they were completely ignorant of the meaning of Origen’s argument.