Luther's spiritual sufferings continued to afflict him for several months, and until the close of the year. Though he had known them, he said, from his youth, he could never have expected that they would prove so severe. He found them very similar to those attacks and struggles which he had had to endure in early life. The invasion of the plague, and the parting from all his intimate friends except Bugenhagen, must have contributed to increase them. He was just now deeply shocked and agitated by the news of the death of a faithful companion in the faith, the Bavarian minister Leonard Käser or Kaiser, who was publicly burnt on August 16, 1527, in the town of Scherding. Luther broke out, as he had done after Henry of Zütphen's martyrdom, into a lamentation of his own unworthiness compared with such heroes. He published an account of Leonard and his end, which had been sent him by Michael Stiefel, adding a preface and conclusion of his own. About the same time he composed a consolatory tract for the Evangelical congregation at Halle-on-the-Saale, whose minister Winkler had been murdered in the previous April. In the autumn a new controversial treatise was published against him by Erasmus, which he rightly described as a product of snakes; and he now stood in the midst of the contest between Zwingli and Oecolampadius. He exclaimed once in a letter to Jonas, 'O that Erasmus and the Sacramentarians (Zwingli and his friends) could only for a quarter of an hour know the misery of my heart. I am certain that they would then honestly be converted. Now my enemies live, and are mighty, and heap sorrow on sorrow upon me, whom God has already crushed to the earth.'