John Newton: There are many who stumble in the noon-day, not for want of light, but for want of eyes.

A blind man, if ingenious and inquisitive, may learn to talk about the light, the sun, or the rainbow, in terms borrowed from those who have seen them; but it is impossible that he can have (I mean a man born blind) a just idea of either; and whatever hearsay knowledge he may have acquired, he can hardly talk much upon these subjects without betraying his real ignorance… Nor can all the learning or study in the world enable any person to form a suitable judgment of divine truth, till the eyes of his mind are opened, and then he will perceive it at once.

…There are many who stumble in the noon-day, not for want of light, but for want of eyes; and they who now see, were once blind even as others, and had neither power nor will to enlighten their own minds…

…This spiritual sight and faculty is that which may be principally considered as inherent in a believer. He has no stock of grace, or comfort, or strength, in himself. He needs continual supplies; and if the Lord withdraws from him, he is as weak and unskilful after he has been long engaged in the Christian warfare, as he was when he first entered upon it. The eye is of little present use in the dark; for it cannot see without light. But the return of light is no advantage to a blind man. A believer may be much in the dark; but his spiritual sight remains. Though the exercise of grace may be low, he knows himself, he knows the Lord, he knows the way of access to a throne of grace. His frames and feelings may alter; but he has received such a knowledge of the person and offices, the power and grace, of Jesus the Saviour, as cannot be taken from him; and he could withstand even an angel that should preach another gospel, because he has seen the Lord

— John Newton

From “Letter XXI: I Was Once Blind But Now I See,” John Newton, Richard Cecil, The Works of the John Newton, vol. 1 (London: Hamilton, Adams & Co., 1824), 283, 286, 288-289.

John Newton was indeed a scoundrel who bartered in the human slave trade. Yet, a violent storm upon the sea, and near ship wreck, brought him to call upon the Lord for deliverance. Coming out of this experience, he experienced a spiritual awakening, and began regularly reading the Scriptures and praying. Supernatural transformation began to take place in Newton’s life, over time he abandoned the slave trade, and then became an abolitionist. Having been brought out the kingdom of darkness into the kingdom of God, Newton proclaimed: Amazing grace! how sweet the sound, | That saved a wretch like me! | I once was lost, but now am found, | Was blind, but now I see.

John Newton (1725–1807) was an English slave trader who later came to faith and became an Anglican minister, abolitionist, and hymn writer. Amazing Grace is his best-known hymn. Newton worked alongside William Wilberforce to help found the Society for Effecting the Abolition of the Slave Trade, also called the Anti-Slavery Society. He also authored Thoughts Upon the African Slave Trade, a powerful critique of the industry he once participated in. His efforts played a significant role in the eventual abolition of the slave trade in the British Empire.