Here's a Quote from John Newton...

... to William Wilberforce in 1796 upon the defeat of his proposal to end the slave trade in the English colonies. Not knowing it would be another 11 years of sustained effort before success, Wilberforce was expressing to his old friend Newton (pictured here) his willingness to consider retirement from public life. Here is Newton's reply, which convinced Wilberforce to stay the course.

Daniel, likewise, was a public man, and in critical circumstances; but he trusted in the Lord; was faithful in his department, and therefore though he had enemies, they could not prevail against him.

Indeed the great point for our comfort in life is to have a well-grounded persuasion that we are where, all things considered, we ought to be. Then it is no great matter whether we are in public or in private life, in a city or a village, in a palace or a cottage. The promise, "My grace is sufficient for thee," is necessary to support us in the smoothest scenes, and is equally able to support us in the most difficult. . . .

[Christ] is always near. He knows our wants, our dangers, our feelings, our fears. By looking to him we are enlightened and made strong out of weakness. With his wisdom for our guide, his power for our protection, his fullness for our supply, and proposing his glory as our chief end, and placing our happiness in his favour, in communion with him, and communications from Him, we shall be able to "withstand in the evil day, and having done all to stand."

Source of Quote: William Wilberforce: A Hero for Humanity by Kevin Belmonte (Zondervan, 2007, pages 137,138)

John Newton is the author of the hymn Amazing Grace, which also serves as the title to the wonderful film that captures the life of William Wilberforce (see pdf study guide).