The grand work of the Christian in the spread of the gospel, is to witness for Jesus, to tell the story of the cross. But mark ye! and mark ye well! not that alone. That would be the story of a dead Saviour. Ours, thanks be to God is a living Saviour, ever living to make intercession for us. The story of the resurrection and ascension must be added to the story of the crucifixion and burial. But mark ye again! and mark well! not this alone this would be but the story of an absent Saviour. Ours, to our joy unspeakable, is a present Saviour, mighty to save, able to deliver, from all the power of the world, the flesh, and the devil. The story of Pentecost must be added to that of Calvary and Olivet [the Ascension]– the story of the return of Jesus in omnipresence and omnipotence, by the Holy Spirit, to be with all his disciples every where, even unto the end of the world [John 14:17,18,23].
It is ours to witness for Jesus; but our testimony cannot go beyond our experience. With the apostles, we cannot but speak the things we have seen and felt; but the things we have not seen and felt we cannot speak effectively and convincingly. The Holy Spirit must first witness to us, before we can witness to others, the things of experience. The convinced soul … may testify for the law in its heart-searching length and breadth, and the converted soul may testify for the gospel in its power to bring sweet Assurance of sins forgiven and the hope of heaven, but it is only him who has also found by similar deeper experience the way of sanctification by faith, who can point to Jesus as the deliverer from [intentional] sin in like manner as from its penalty.
And then, too, as we have already illustrated, in each successive stage of advancement, there is a new spring and strength of force given to all that has gone before.In advancing we do not lose the things that we leave behind, as we press onward to the mark, but double the old store in gaining the new.
The apostles did not more than half understand the significance of all that Jesus did and said while he was with them in person in the days of his flesh.
But afterward, when in the power of the Holy Spirit, he came to them and dwelt with them, and within them, from the day of Pentecost onward, then with all that was new to them, in this new experience of theirs, there came also such a recollection of all that Jesus had said and done, with such a new fulness of significance in all, as made it all like a new story to them.
[Consider that] Luther and D’ Aubigne, in their after and deeper experience, found the word of God illuminated anew to them, with a richer and fuller significance of truth and grace. The things they understood before, they understood better now; and the things that came home to them with power before, came home to them with a new power now; while at the same time they saw Jesus, and felt the blessedness of His presence and might now in a new relation entirely, viz. as their sanctification, and in all this they were witnesses for Jesus in the fulness of the new power received from God, in the new experience of his wisdom and grace in providing a way of escape from [willful] sin itself as easy and plain as the way of escape from the wrath to come [Rom. 6:6].
This accounts for the new spring and power of usefulness given to these men. Useful before, they were a hundred-fold more so afterwards. Their knowledge of science was not extended. They were not advanced to new and higher posts of honor and power. Their positions and circumstances remained as they were before, but they had made new discoveries in the science of salvation, and gained new positions in the world of faith, and the fire was kindled in their hearts into a new glow of fervency and light. The waters of life came welling up anew in their souls, overflowing and flowing out in rivers, in their testimony, oral and written, from pulpit and press, concerning Jesus, to a sin ruined world.
An excerpt from The Higher Christian Life, by William Boardman, ch. 6. Henry Hoyt Publishers: Boston, 1858. https://archive.org/details/higherchristianlife00boarrich One of the many who have been impacted through this study was A.B. Simpson. His grace awakening culminated in the formation of The Christian and Missionary Alliance. Title, italics, bracketed Scriptures, footnote, and references have been added. – JBW
 Martin Luther was famous leader of the Protestant Reformation and translator of the New Testament into German. Jean Henri Merle d’Aubigné was a pastor and the most popular church historian of the nineteenth century; served in Geneva.