“By way of introduction, we shall briefly recall what constitutes the one thing necessary for every Christian, and we shall also recall how urgently this question is being raised at the present time.
As everyone can easily understand, the interior life is an elevated form of intimate conversation which everyone has with himself as soon as he is alone, even in the tumult of a great city. From the moment he ceases to converse with his fellow men, man converses interiorly with himself about what preoccupies him most. This conversation varies greatly according to the different ages of life; that of an old man is not that of a youth. It also varies greatly according as a man is good or bad.
As soon as a man seriously seeks truth and goodness, this intimate conversation with himself tends to become conversation with God. Little by little, instead of seeking himself in everything, instead of tending more or less consciously to make himself a center, man tends to seek God in everything, and to substitute for egoism love of God and of souls in Him. This constitutes the interior life. No sincere man will have any difficulty in recognizing it. The one thing necessary which Jesus spoke of to Martha and Mary (1) consists in hearing the word of God and living by it.”