Again what might have been called the Missionary's holiday was employed in the most earnest labours. In hurrying from place to place, from meeting to meeting, the Missionary perhaps endured as much fatigue as from the heavy work in India. Thus he wrote in the bitterly cold month of November, when on one of his numerous journeys. "Since I left the pulpit on Sunday I have scarcely yet got into anything like warmth, either by night or day. I have felt as if the cold were oozing through my whole body from head to foot . . . And what with unseasoned rooms and unseasoned beds and frosty air, and chills after full meetings, I feel as if it were a kind of living martyrdom to be encountering all this . . . But most gladly would I bear all, and a great deal more, if possible, for the sake of Him who so loved us as to lay down His very life for us, were I to behold substantial fruit to His praise and glory. I must however leave all to Him. My own shortcomings are ever before me . . . "Nothing sustains me but the divine assurance that the blood of Jesus cleanseth from all sin. Blessed Saviour! Who would not cheerfully toil and suffer for Thee!" Dr. Duff, exhausted, yet struggling on still, thus wrote to his wife when he was engaged on one of his preaching tours. "It is some relief to the mind to get disburdened, and to whom can I disburden it if not to you, the partner of my joys and sorrows for nearly a quarter of a century. No one can over fully know how much I often suffer both in mind and body in the midst of these frequent, prolonged, and violent exertions: and to none but yourself can I ever moot the subject except in the vaguest and most general terms. In the excitement of speaking, the spirit forgets the fragility of the body, and therefore people think me strong. Oh! if they could see me in my solitary chamber all alone . . . the whole frame feverish, the whole nervous system from the brain downwards in a state of total unrest. The very tendency to sleep gone. Going to bed, as this morning, at half past one, not from sleepiness but from inability to sit up longer from exhaustion. Turning and tossing from side to side, and longing for sleep . . . Getting up, disquieted and unrefreshed, to meet a company at breakfast, with aching head besides and sorish throat . . . Yet, the Lord be praised; in the midst of all this I have intervals of real spiritual enjoyment, indeed, when most weak and pained often is that enjoyment proportionally increased. And then the favour which the Lord shows me in the sight of His people, and the good so often unexpectedly achieved, all this makes me feel that what I suffer is the discipline of a Father's rod to keep me humble in walking before him." Exhausted as the Missionary was, he could not refuse what he felt to be a call from God to visit America, as he was earnestly entreated to do.