The Imitation of Christ, by Thomas a Kempis, tr. by William Benham , at sacred-texts.com
"My Son, it is better and safer for thee to hide the grace of devotion, and not to lift thyself up on high, nor to speak much thereof, nor to value it greatly; but rather to despise thyself, and to fear as though this grace were given to one unworthy thereof. Nor must thou depend too much upon this feeling, for it can very quickly be turned into its opposite. Think when thou art in a state of grace how miserable and poor thou art wont to be without grace. Nor is there advance in spiritual life in this alone, that thou hast the grace of consolation, but that thou humbly and unselfishly and patiently takest the withdrawal thereof; so that thou cease not from the exercise of prayer, nor suffer thy other common duties to be in anywise neglected; rather do thy task more readily, as though thou hadst gained more strength and knowledge; and do not altogether neglect thyself because of the dearth and anxiety of spirit which thou feelest.
2. "For there are many who, when things have not gone prosperous with them, become forthwith impatient or slothful. For the way of a man is not in himself,(1) but it is God's to give and to console, when He will, and as much as He will, and whom He will, as it shall please Him, and no further. Some who were presumptuous because of the grace of devotion within them, have destroyed themselves, because they would do more than they were able, not considering the measure of their own littleness, but rather following the impulse of the heart than the judgment of the reason. And because they presumed beyond what was well-pleasing unto God, therefore they quickly lost grace. They became poor and were left vile, who had built for themselves their nest in heaven; so that being humbled and stricken with poverty, they might learn not to fly with their own wings, but to put their trust under My feathers. They who are as yet new and unskilled in the way of the Lord, unless they rule themselves after the counsel of the wise, may easily be deceived and led away.
3. "But if they wish to follow their own fancies rather than trust the experience of others, the result will be very dangerous to them if they still refuse to be drawn away from their own notion. Those who are wise in their own conceits, seldom patiently endure to be ruled by others. It is better to have a small portion of wisdom with humility, and a slender understanding, than great treasures of sciences with vain self-esteem. It is better for thee to have less than much of what may make thee proud. He doeth not very discreetly who giveth up himself entirely to joy, forgetting his former helplessness and the chaste fear of the Lord, which feareth to lose the grace offered. Nor is he very wise, after a manly sort, who in time of adversity, or any trouble whatsoever, beareth himself too despairingly, and feeleth concerning Me less trustfully than he ought.
4. "He who in time of peace willeth to be oversecure shall be often found in time of war overdispirited and full of fears. If thou knewest always how to continue humble and moderate in thyself, and to guide and rule thine own spirit well, thou wouldest not so quickly fall into danger and mischief. It is good counsel that when fervour of spirit is kindled, thou shouldest meditate how it will be with thee when the light is taken away. Which when it doth happen, remember that still the light may return again, which I have taken away for a time for a warning to thee, and also for mine own glory. Such a trial is often more useful than if thou hadst always things prosperous according to thine own will.
5. "For merits are not to be reckoned by this, that a man hath many visions or consolations, or that he is skilled in the Scriptures, or that he is placed in a high situation; but that he is grounded upon true humility and filled with divine charity, that he always purely and uprightly seeketh the honour of God, that he setteth not by himself, but unfeignedly despiseth himself, and even rejoiceth to be despised and humbled by others more than to be honoured."
(1) Jeremiah x. 23.