“Oh, that You would rend the heavens! That You would come down!” Millions have prayed that, and pray it now. Has it ever happened? Yes, God has come down; both the Bible and Christian history bear witness to it. In the Day of Thy Power is filled with plentiful quotations from eyewitnesses of revival and with inescapable biblical authority for such “times of refreshing . . . from the presence of the Lord.” It unfolds the conditions by which God still comes, as in apostolic days, with “mighty signs and wonders, by the power of the Spirit of God.” “As I read the manuscript,” Norman Grubb recalled, “it had the effect of confronting me with „the word of the Lord‟ and demanding an answer. . . . I believe it will have a like effect on all who read it with „ears to hear.‟” This first book of Arthur Wallis, written in 1956, was an immediate success when first published and has become a classic on the subject of revival.