Charles H. Spurgeon on Psalms 19:8

"The statutes of the Lord are right." His precepts and decrees are founded in righteousness, and are such as are right or fitted to the right reason of man. As a physician gives the right medicine, and a counsellor the right advice, so does the Book of God. "Rejoicing the heart." Mark the progress; he who was converted was next made wise and is now made happy; that truth which makes the heart right then gives joy to the right heart. Free-grace brings heart-joy. Earthborn mirth dwells on the lip, and flushes the bodily powers; but heavenly delights satisfy the inner nature, and fill the mental faculties to the brim. There is no cordial of comfort like that which is poured from the bottle of Scripture.

"Retire and read thy Bible to be gay." "The commandment of the Lord is pure." No mixture of error defiles it, no stain of sin pollutes it; it is the unadulterated milk, the undiluted wine. "Enlightening the eyes," purging away by its own purity the earthly grossness which mars the intellectual discernment: whether the eye be dim with sorrow or with sin, the Scripture is a skilful occulist, and makes the eye clear and bright. Look at the sun and it puts out your eyes, look at the more than sunlight of Revelation and it enlightens them; the purity of snow causes snow-blindness to the Alpine traveller, but the purity of God's truth has the contrary effect, and cures the natural blindness of the soul. It is well again to observe the gradation; the convert becomes a disciple and next a rejoicing soul, he now obtains a discerning eye and as a spiritual man discerneth all things, though he himself is discerned of no man.