Charles H. Spurgeon on Psalms 119:37

Turn away mine eyes, etc. Having prayed for his heart, he now prayeth for his eyes also. Omnia a Deo petit, docens, illum omnia efficere. By the eyes oftentimes, as by windows, death enters into the heart; therefore to keep the heart in a good estate three things are requisite, First, careful study of the senses, specially of the eyes; for it is a righteous working of the Lord, ut qui exteriori oculo negligenter utitur, intertori non injuste caecetur that he who negligently useth the external eye of his body, should punished with blindness in the internal eye of his mind. And for this cause Nazianzen, deploring the calamities of his soul, wished that a door might set before his eyes and ears, to close them when they opened to anything that is not good; malis autem sua sponte uturumque clauderetur. The second thing is, a subduing of the body by discipline. And the third is, continuance in prayer. William Cowper.