Some years ago I was at work one forenoon in my study, and very busy, when my mind became distracted and I could not think out my sermon. It was as if a side stream had rushed into a river, confusing and discolouring the water; and at last, when the confusion was over and the water was clear, I was conscious of a new subject. Some short time before, a brother minister, whom I knew well and greatly respected, had suffered from dissension in his congregation and had received our sincere sympathy. He had not, however, been in my mind that day, but now I found myself unable to think of anything else. My imagination began to work in the case till I seemed, in the midst of the circumstances, as if I were the sufferer. Very soon a suggestion arose and grew into a commandment, that I should offer to take a day's duty for my brother. At this point I pulled myself together and resisted what seemed a vagrant notion. "Was such a thing ever heard of,--that for no reason save a vague sympathy one should leave one's own pulpit and undertake the work of another, who had not asked him and might not want him?" So I turned to my manuscript to complete a broken sentence, but could only write "Dear A. B." Nothing remained but to submit to this mysterious dictation and compose a letter as best one could, till the question of date arose. There I paused and waited, when an exact day came up before my mind, and so I concluded the letter. It was, however, too absurd to send; and so, having rid myself of this irrelevancy, I threw the letter into the fire and set to work again; but all day I was haunted by the idea that my brother needed my help. In the evening a letter came from him, written that very forenoon, explaining that it would be a great service to him and his people if I could preach some Sunday soon in his church, and that, owing to certain circumstances, the service would be doubled if I could come on such and such a day; and it was my date! My course was perfectly plain, and I at once accepted his invitation under a distinct sense of a special call, and my only regret was that I had not posted my first letter.