This hymn…was doubtless prepared for some occasion of protracted service, some gathering of a large body of people. It was the custom…to introduce the autumn and winter work with a continuous assemblage of church members; it was believed that united prayer would stimulate the graces of true believers, and fervid exhortations would arouse the laggard ones to fresh duty; and it was always understood that, when the saints came back to faithful activity, the Holy Spirit would surely answer with energy in the conversion of souls. "No doubt," writes good William Gurnall, the famous divine of the seventeenth century; "no doubt the prayers which the faithful put up to heaven from under their private roofs are very acceptable to God; but if a saint’s single voice in prayer be so sweet to his ear, much more the church choir, his saints’ prayers in concert together. A father is glad to see any one of his children, and makes him welcome when he visits him; but much more when they come together; the greatest feast when they all meet at his house."
Annotations upon Popular Hymns by Charles S. Robinson, New York: Hunt & Eaton, 1893