Here are some thoughts by John Newton:
The Lord appoints occasions and turns in life, which try our spirits. There are particular seasons when temptations are suited to our frames, tempers, and situations; and there are times when he is pleased to withdraw, and to permit Satan's approach, that we may feel how vile we are in ourselves. We are prone to spiritual pride, to self-dependence, to vain confidence, to creature attachments, and a train of evils. The Lord often discovers to us one sinful disposition by exposing us to another. He sometimes shows us what he can do for us and in us; and at other times how little we can do, and how unable we are to stand without him.
By a variety of these exercises, through the over-ruling and edifying influences of the Holy Spirit, 'B' [the maturing believer] is trained up in a growing knowledge of himself and of the Lord. He learns to be more distrustful of his own heart, and to suspect a snare in every step he takes. The dark and disconsolate hours which he has brought upon himself in times past, make him doubly prize the light of God's countenance, and teach him to dread whatever might grieve the Spirit of God, and cause him to withdraw again. The repeated and multiplied pardons which he has received, increase his admiration of, and the sense of his obligations to, the rich sovereign abounding mercy of the covenant. Much has been forgiven him, therefore he loves much, and therefore he knows how to forgive and pity others. He does not call evil good, or good evil; but his own experiences teach him tenderness and forbearance. He exercises a spirit of meekness towards those who are overtaken in a fault; and his attempts to restore such, are according to the pattern of the Lord's dealings with himself.2
1. Extravagant Grace: God's Glory Displayed in Our Weakness, Barbara Duguid, P&R Publishing, 2013, pp 51-61.
2. Letters of John Newton, Banner of Truth Trust, 1965, pg. 22. Online letter here. (italics mine)
(Adapted from a previous blog post.)