The Imitation of Christ, by Thomas a Kempis, tr. by William Benham , at sacred-texts.com
There is naturally in every man a desire to know, but what profiteth knowledge without the fear of God? Better of a surety is a lowly peasant who serveth God, than a proud philosopher who watcheth the stars and neglecteth the knowledge of himself. He who knoweth himself well is vile in his own sight; neither regardeth he the praises of men. If I knew all the things that are in the world, and were not in charity, what should it help me before God, who is to judge me according to my deeds?
2. Rest from inordinate desire of knowledge, for therein is found much distraction and deceit. Those who have knowledge desire to appear learned, and to be called wise. Many things there are to know which profiteth little or nothing to the soul. And foolish out of measure is he who attendeth upon other things rather than those which serve to his soul's health. Many words satisfy not the soul, but a good life refresheth the mind, and a pure conscience giveth great confidence towards God.
3. The greater and more complete thy knowledge, the more severely shalt thou be judged, unless thou hast lived holily. Therefore be not lifted up by any skill or knowledge that thou hast; but rather fear concerning the knowledge which is given to thee. If it seemeth to thee that thou knowest many things, and understandest them well, know also that there are many more things which thou knowest not. Be not high-minded, but rather confess thine ignorance. Why desirest thou to lift thyself above another, when there are found many more learned and more skilled in the Scripture than thou? If thou wilt know and learn anything with profit, love to be thyself unknown and to be counted for nothing.
4. That is the highest and most profitable lesson, when a man truly knoweth and judgeth lowly of himself. To account nothing of one's self, and to think always kindly and highly of others, this is great and perfect wisdom. Even shouldest thou see thy neighbor sin openly or grievously, yet thou oughtest not to reckon thyself better than he, for thou knowest not how long thou shalt keep thine integrity. All of us are weak and frail; hold thou no man more frail than thyself.