Luther, who by this time was in his forties, was still a single man. This did not prevent him, however, from powerfully preaching on the virtues and importance of marriage. Some, like the Bavarian noblewoman Argula von Grumbach, began to wonder why he himself did not marry. Luther responded in a letter to Spalatin (November 30, 1524):
I am grateful for what Argula writes about my wedding plans; I am not surprised about such gossip, since so many other bits of gossip are around concerning me. Nevertheless give her my thanks and tell her I am in God’s hand as a creature whose heart God may change and rechange, kill and revive again at any moment. Nevertheless, the way I feel now, and have felt thus far, I will not marry. It is not that I do not feel my flesh or sex, since I am neither wood nor stone, but my mind is far removed from marriage, since I daily expect death and the punishment due to a heretic. Therefore I shall not limit God’s work in me, nor shall I rely on my own heart. Yet I hope God does not let me live long.
Luther here acknowledges the presence of sexual desire. Earlier, in connection with a sermon on Isaac’s marriage to Rebekah at the age of forty, Luther—himself around that age—had written: “Nature is so constituted that it feels sexual desires (fervores carnis) at about the age of twenty. To bear and to overcome these until the age of forty is truly a grievous and great burden.” But at this time, Luther truly believed that his death was imminent and that God had called him to a life of singleness. Hence marriage would be unhelpful and unnecessary, and chastity could be maintained.
A few years earlier, in his Estate of Marriage (1522) Luther had spoken of those rare Paul-type individuals who were able to refrain from sex and marriage for the purpose of ministry involvement. By implication including himself in this category, he wrote of those:
spiritually rich and exalted persons, bridled by the grace of God, who are equipped for marriage by nature and physical capacity and nevertheless voluntarily remain celibate. These put it this way, “I could marry if I wish, I am capable of it. But it does not attract me. I would rather work on the kingdom of heaven, i.e., the gospel, and beget spiritual children.” Such persons are rare, not one in a thousand, for they are a special miracle of God. No one should venture on such a life unless he finds God’s grace to be so powerful within him that the divine injunctions, “Be fruitful and multiply,” has no place in him.
Luther’s reservations about his own prospects for marriage did not deter him from enthusiastically counseling others to marry! Spalatin wanted Luther to encourage Wolfgang Reissenbusch, the preceptor of the Antonians in Lichtenburgh, to get married. So on March 27, 1525, Luther wrote him a letter which was to be later published as a booklet. Luther wrote:
Your body urges you to marry and needs it; God wills and forces it. What will you do about it? It would also be a fine, noble example if you married, that would help many feeble ones, broaden their paths and give them more scope, so many others might escape the dangers of the flesh and follow you.”
On April 10, 1525, Luther offered similar counsel to Spalatin: “Why don’t you go on and get married? I urge matrimony on others with so many arguments that I am myself almost moved to marry, though our enemies do not cease to condemn that way of life, and our wiseacres laugh at it all the time.” This is the first recorded hint that perhaps Luther is opening up to the possibility of being married.
One week later Luther, along with Melanchthon and John Agricola, left on a trip to Eisleben to discuss the formation of a Christian school. Apparently marriage was very much on his mind. On April 16, the day of the trip, he paused to pen a letter to Spalatin about his traveling plans. At the end of the note he could not refrain from making a few more jokes about him the possibility of marriage:
Incidentally, regarding what you are writing about my marrying: I do not want you to wonder that a famous lover like me does not marry. It is rather strange that I, who so often write about matrimony and get mixed up with women, have not yet turned into a woman, to say nothing of not having married one. Yet if you want me to set an example, look, here you have the most powerful one, for I have had three wives simultaneously, and loved them so much that I have lost two who are taking other husbands; the third I can hardly keep with my left arm, and she, too, will probably be snatched away from me. But you are a sluggish lover who does not dare to become the husband of even one woman. Watch out that I, who have no thought of marriage at all, do not some day overtake you too eager suitors—just as God usually does things which are least expected. I am saying this seriously to urge you to do what you are intending.
On April 21 he left Eisleben for Thuringia to visit his parents, friends, and relatives, and also to advocate for peace with regard to the uprising of the peasants. When he mentioned the idea of marriage to his parents—perhaps again in a joking manner—his father enthusiastically encouraged him to follow through on marriage, expecting that Martin would have a son through whom he would pass along the family name.
The straw the broke the camel’s back, however, may have come when Hieronymus Schurrf wrote: “If this monk [Luther] were to take a wife, then all the world and the very devil would laugh, and [Luther] himself would ruin everything that he had created.” On May 4, Luther responded in a letter to John Rühel, offering the first definitive statement that he was thinking of marrying Katherine: “If I can arrange it, I will marry Kate in defiance of the devil and all his adversaries.” In early June he wrote to Albrecht von Mainz, encouraging him to marry: “If my marrying will strengthen him, I am ready. I believe in marriage.”
He later recounted: “As I considered taking Kate as my wife, I entreated our Lord God earnestly to help me.” Though we don’t know the details, we do know that Luther proposed to Katherine at the Cranach residence. And that she accepted.
On June 10, in response to Spalatin’s question about Luther’s view of how long an engagement should be, he wrote: “Don’t put off till tomorrow! By delay Hannibal lost Rome. By delay Esau forfeited his birthright. Christ said, ‘Ye shall seek me, and ye shall not find.’ Thus Scripture, experience, and all creation testify that the gifts of God must be taken on the wing.” Just three days later, Luther heeded his own counsel by becoming officially engaged and married on the very same day! Luther later wrote of the danger of putting off marriage: “We should help partners get together with no delay. If I had not married quietly with the knowledge of only a few friends, people would certainly have prevented it.”
 A Christian Writing for W. Reissenbusch, Encouraging Him to Marry, in LW 44:300-301. Reissenbach married Hanna Hertzog on April 26, 1525—one month after Luther wrote his letter.
 Martin Luther, D. Martin Luthers Werke: Briefweschel [hereafter WABr], 15 vols, J. F. K. Knaake, G. Kawerau, et al., eds., Weimar (1930-85), 3:479-482.