Charles H. Spurgeon on Psalms 119:16

I will not forget. Delight prevents forgetfulness: the mind will run upon that which the heart delighteth in; and the heart is where the treasure is (Matthew 6:21). Worldly men that are intent upon carnal interests, forget the word, because it is not their delight. If anything displeases us, we are glad if we can forget it; it is some release from an inconvenience, to take off our thoughts from it; but it doubles the contentment of a thing that we are delighted in, to remember it, and call it to mind. In the outward school, if a scholar by his own averseness from learning, or by the severity and imprudence of his master, hath no delight in his book, all that he learns is lost and forgotten, it goeth in at one ear, and out at the other: but this is the true art of memory, to cause them to delight in what they learn. Such instructions as we take in with sweetness, they stick with us, and run in our minds night and day. So saith David here, I will delight myself in thy statutes: I will not forget thy word. Thomas Manton.