The Imitation of Christ, by Thomas a Kempis, tr. by William Benham , at sacred-texts.com
"My Son, if thou set thy peace on any person because thou hast high opinion of him, and art familiar with him, thou shalt be unstable and entangled. But if thou betake thyself to the ever-living and abiding Truth, the desertion or death of a friend shall not make thee sad. In Me ought the love of thy friend to subsist, and for My sake is every one to be loved, whosoever he be, who appeareth to thee good, and is very dear to thee in this life. Without Me friendship hath no strength or endurance, neither is that love true and pure, which I unite not. Thou oughtest to be so dead to such affections of beloved friends, that as far as in thee lieth, thou wouldst rather choose to be without any companionship of men. The nearer a man approacheth to God, the further he recedeth from all earthly solace. The deeper also he descendeth into himself, and the viler he appeareth in his own eyes, the higher he ascendeth towards God.
2. "But he who attributeth anything good to himself, hindereth the grace of God from coming to him, because the grace of the Holy Ghost ever seeketh the humble heart. If thou couldst make thyself utterly nothing, and empty thyself of the love of every creature, then should it be My part to overflow unto thee with great grace. When thou settest thine eyes upon creatures, the face of the Creator is withdrawn from thee. Learn in all things to conquer thyself for thy Creator's sake, then shalt thou be able to attain unto divine knowledge. How small soever anything be, if it be loved and regarded inordinately, it holdeth us back from the highest good, and corrupteth."