I refer to the Imitation of Christ, by Kempis.
"TURN your attention upon yourself and beware of judging the deeds of other men, for in judging others a man labors vainly, often makes mistakes, and easily sins; whereas, in judging and taking stock of himself he does something that is always profitable.
We frequently judge that things are as we wish them to be, for through personal feeling true perspective is easily lost.
If God were the sole object of our desire, we should not be disturbed so easily by opposition to our opinions. But often something lurks within or happens from without to draw us along with it.
Many, unawares, seek themselves in the things they do. They seem even to enjoy peace of mind when things happen according to their wish and liking, but if otherwise than they desire, they are soon disturbed and saddened. Differences of feeling and opinion often divide friends and acquaintances, even those who are religious and devout.
An old habit is hard to break, and no one is willing to be led farther than he can see.
If you rely more upon your intelligence or industry than upon the virtue of submission to Jesus Christ, you will hardly, and in any case slowly, become an enlightened man. God wants us to be completely subject to Him and, through ardent love, to rise above all human wisdom."