Thomas a Kempis, The Imitation of Christ 1.11

Of seeking peace of mind and of spiritual progress

1. We may enjoy abundance of peace if we refrain from busying ourselves with the sayings and doings of others, and things which concern not ourselves. How can he abide a long time in peace who occupies himself with other men's matters, and with things without himself, and meanwhile pays little or rare heed to the self within? Blessed are the single-hearted, for they shall have abundance of peace.

2. How came it to pass that many of the Saints were so perfect, so contemplative of Divine things? Because they steadfastly sought to mortify themselves from all worldly desires, and so were enabled to cling with their whole heart to God, and be free and at leisure for the thought of Him. We are too much occupied with our own affections, and too anxious about transitory things. Seldom, too, do we entirely conquer even a single fault, nor are we zealous for daily growth in grace. And so we remain lukewarm and unspiritual.

3. Were we fully watchful of ourselves, and not bound in spirit to outward things, then might we be wise unto salvation, and make progress in Divine contemplation. Our great and grievous stumbling-block is that, not being freed from our affections and desires, we strive not to enter into the perfect way of the Saints. And when even a little trouble befalls us, too quickly are we cast down, and fly to the world to give us comfort.

4. If we would quit ourselves like men, and strive to stand firm in the battle, then should we see the Lord helping us from Heaven. For He Himself is always ready to help those who strive and who trust in Him; yea, He provides for us occasions of striving, to the end that we may win the victory. If we look upon our progress in religion as a progress only in outward observances and forms, our devoutness will soon come to an end. But let us lay the axe to the very root of our life, that, being cleansed from affections, we may possess our souls in peace.

5. If each year should see one fault rooted out from us, we should go quickly on to perfection. But on the contrary, we often feel that we were better and holier in the beginning of our conversion than after many years of profession. Zeal and progress ought to increase day by day; yet now it seems a great thing if one is able to retain some portion of his first ardour. If we would put some slight stress on ourselves at the beginning, then afterwards we should be able to do all things with ease and joy.

6. It is a hard thing to break through a habit, and a yet harder thing to go contrary to our own will. Yet if you overcome not slight and easy obstacles, how you you overcome greater ones? Withstand your will at the beginning, and unlearn an evil habit, lest it lead you little by little into worse difficulties. Oh, if you knew what peace to yourself your holy life should bring to yourself, and what joy to others, I think you would be more zealous for spiritual profit.