The Conferences Of John Cassian by John Cassian
Chapter VII. The answer on the difference of customs in the two countries.
Germanus: Although we ought to be most grateful for the teaching of those men who taught us from our youth up to attempt great things, and, by giving us a taste of their excellence, implanted in our hearts a splendid thirst for perfection, yet if any reliance is to be placed on our judgment, we cannot draw any comparison between these customs and those which we learnt there, so as to hold our tongues about the inimitable purity of your life, which we believe is granted to you not only owing to the concentration of your mind and aim, but also owing to the aid and assistance of the place itself. Wherefore we do not doubt that for the following of your grand perfection this instruction which is given to us is not enough by itself, unless we have also the help of the life, and a long course of instruction somewhat dissolves the coldness of our heart by daily training.