On July 16, 1505, Martin Luther, then a student at the University of Erfurt, invited his friends and acquaintances to a farewell supper. He wished to see them about him for the last time before his approaching retirement to the cloister. "The bright, cheerful young fellow," as his later pupil, Mathesius, calls him, was a favourite in his own circle. Those assembled to bid him farewell, amongst whom were also "honest, virtuous maidens and women," were doubtless somewhat taken aback at their friend's sudden determination to leave the world; but Luther was outwardly "beyond measure cheerful" and showed himself so light of heart that he played the lute while the wine-cup circled round.
On the following morning—it was the feast of St. Alexius, as Luther remembered when an old man—some of his fellow-students accompanied him to the gate of the Augustinian monastery and then, with tears in their eyes, saw the doors close upon him. The Prior, who was already apprised of the matter, greeted the timid new-comer, embraced him, and then, in accordance with the Rule, confided him to the Master of Novices to be initiated into the customs of the community.
In the quiet monastic cell and amid the strange new surroundings the student was probably able little by little to master the excitement which, though hidden from outsiders, raged within his breast; for the determination to become a monk had been arrived at under strange, soul-stirring circumstances. He was on his way back to Erfurt, after a visit to his parents' house, when, near Stotternheim, he was overtaken by a thunderstorm, and as a flash of lightning close beside him threatened him "like a heavenly vision," he made the sudden vow: "Save me, dear St. Anne, and I will become a monk." He appears also at that very time to have been reduced to a state of great grief and alarm by the sudden death of a dear comrade, also a student, who had been stabbed, either in a quarrel or in a duel. Thus the thoughts which had perhaps for long been attracting his serious temperament towards the cloister ripened with overwhelming rapidity. Could we but take a much later assertion of his as correct, the reason of his resolve was to be found in a certain vexation with himself: because he "despaired" of himself, he once says, therefore did he retire into the monastery.