The Imitation of Christ, by Thomas a Kempis, tr. by William Benham , at sacred-texts.com
Blessed is he who understandeth what it is to love Jesus, and to despise himself for Jesus' sake. He must give up all that he loveth for his Beloved, for Jesus will be loved alone above all things. The love of created things is deceiving and unstable, but the love of Jesus is faithful and lasting. He who cleaveth to created things will fall with their slipperiness; but he who embraceth Jesus will stand upright for ever. Love Him and hold Him for thy friend, for He will not forsake thee when all depart from thee, nor will he suffer thee to perish at the last. Thou must one day be separated from all, whether thou wilt or wilt not.
2. Cleave thou to Jesus in life and death, and commit thyself unto His faithfulness, who, when all men fail thee, is alone able to help thee. Thy Beloved is such, by nature, that He will suffer no rival, but alone will possess thy heart, and as a king will sit upon His own throne. If thou wouldst learn to put away from thee every created thing, Jesus would freely take up His abode with thee. Thou wilt find all trust little better than lost which thou hast placed in men, and not in Jesus. Trust not nor lean upon a reed shaken with the wind, because all flesh is grass, and the goodliness thereof falleth as the flower of the field.(1)
3. Thou wilt be quickly deceived if thou lookest only upon the outward appearance of men, for if thou seekest thy comfort and profit in others, thou shalt too often experience loss. If thou seekest Jesus in all things thou shalt verily find Jesus, but if thou seekest thyself thou shalt also find thyself, but to thine own hurt. For if a man seeketh not Jesus he is more hurtful to himself than all the world and all his adversaries.
(1) Isaiah xl. 6.