Thomas a Kempis was a catholic mystic who lived 1380 - 1471. His writings deeply affected John Wesley. These quotes are simple yet challenging and get to the core of true religion. Click the link if you wish to read the whole book.

“The teaching of Christ is more excellent than all the advice of the saints, and he who has His spirit will find in it a hidden manna.”

“Now, there are many who hear the Gospel often but care little for it because they have not the spirit of Christ.”

“Whoever wishes to understand fully the words of Christ must try to pattern his whole life on that of Christ.”

“What good does it do to speak learnedly about  the Trinity if, lacking humility, you displease the Trinity?”

“Indeed it is not learning that makes a man holy and just, but a virtuous life makes him pleasing to God. I would rather feel contrition than know how to define it. For what would it profit us to know the whole Bible by heart and the principles of all the philosophers if we live without grace and the love of God? Vanity of vanities and all is vanity, except to love God and serve Him alone.”

“Every man naturally desires knowledge; but what good is knowledge without fear of God?”

“Indeed a humble countryman who serves God is better than a proud intellectual who neglects his soul to study the course of the stars.”

“If I knew all things in the world and had not charity, what would it profit me before God Who will judge me by my deeds?”

“Shun too great a desire for knowledge, for in it there is much fretting and delusion. Intellectuals like to appear learned and to be called wise. Yet there are many things the knowledge of which does little or no good to the soul, and he who concerns himself about other things than those which lead to salvation is very unwise.”

“Wherefore, if you see another sin openly or commit a serious crime, do not consider yourself better, for you do not know how long you will remain in state of grace. All men are frail, but you must admit that none is more frail than yourself.”