From the writings of A. W. Tozer
"It was the enraptured Rutherford who could shout in the midst of serious and painful trials, "Praise God for the hammer, the file and the furnace."
"The hammer is a useful tool, but the nail, if it had feeling and intelligence, could present another side of the story. For the nail knows the hammer only as an opponent, a brutal, merciless enemy who lives to pound it into submission, to beat it down out of sight and clinch it into place. That is the nail's view of the hammer, and it is accurate except for one thing: The nail forgets that both it and the hammer are servants of the same workman. Let the nail but remember that the hammer is held by the workman and all resentment toward it will disappear. The carpenter decides whose head will be beaten next and what hammer shall be used in the beating. That is his sovereign right. When the nail has surrendered to the will of the workman and has gotten a little glimpse of his benign plans for its future it will yield to the hammer without complaint.
"The file is more painful still, for its business is to bite into the soft metal, scraping and eating away the edges till it has shaped the metal to its will. Yet the file has, in truth, no real will in the matter, but serves another master as the metal also does. It is the master and not the file that decides how much shall be eaten away, what shape the metal shall take, and how long the painful filing shall continue. Let the metal accept the will of the master and it will not try to dictate when or how it shall be filed.
"As for the furnace, it is the worst of all. Ruthless and savage, it leaps at every combustible thing that enters it and never relaxes its fury till it has reduced it all to shapeless ashes. All that refuses to burn is melted to a mass of helpless matter, without will or purpose of its own. When everything is melted that will melt and all is burned that will burn, then and not till then the furnace calms down and rests from its destructive fury.
"With all this known to him, how could Rutherford find it in his heart to praise God for the hammer, the file and the furnace? The answer is simply that he loved the Master of the hammer, he adored the Workman who wielded the file, he worshiped the Lord who heated the furnace for the everlasting blessing of His children. He had felt the hammer till its rough beatings no longer hurt; he had endured the file till he had come actually to enjoy its bitings; he had walked with God in the furnace so long that it had become as his natural habitat."