From the Confessions, Book IV, chapter 12.
If the things of the world delight you, praise God for them but turn your love away from them and give it to their Maker, so that in the things that please you you may not displease him. If your delight is in souls, love them in God, because they too are frail and stand firm only when they cling to him. If they do not, they go their own way and are lost. Love them, then, in him and draw as many with you to him as you can. Tell them, ‘He is the one we should love. He made the world and he stays close to it.’ For when he made the world he did not go away and leave it. By him it was created and in him it exists. Where we taste the truth, God is there. He is in our very inmost hearts, but our hearts have strayed from him. Think well on it, unbelieving hearts (Is 46.8) and cling to him who made you. Stand with him and you shall not fall; rest in him and peace shall be yours. What snags and pitfalls lie before you? Where do your steps lead you? The good things which you love are all from God, but they are good and sweet only as long as they are used to do his will. They will rightly turn bitter if God is spurned and the things that come from him are wrongly loved.
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