Heinrich Bullinger (1504-1575) was an associate and successor of Ulrich Zwingli at Zurich. Some of his writings include a history of the Swiss Reformation, Decades, and Common Places. This quote comes from his Decades (a systematic theology in 50 sermons):
“For when to harden, the Lord calleth man and he resisteth, making himself unworthy of the kingdom of heaven, he doth then permit him unto himself: that is, he leaveth man unto his own corrupt nature, according unto which the heart of man is made stony, which is mollified and made tractable by the only grace of God: therefore the withdrawing of God’s grace is the hardening of man’s heart; and when we are left unto ourselves, then are we hardened” (Heinrich Bullinger, Decades, 3rd Decade, Sermon 10, vol 2, p. 381).
Nothing new here. Bullinger does what multitudes of Reformed (or Calvinist) men do and have done throughout history -- and that is, blatantly deny God's sovereignty as it relates to sinful actions of men. Bullinger's comments are further confirmation that the history and theology of Calvinism is just one long line of tumultuous teapots, short and stout, shaking their handles, and emitting seditious steam from their spouts:
“So, then, to whom He desires, He shows mercy. And to whom He desires, He hardens. You will then say to me, Why does He yet find fault? For who has resisted His will? Yes, rather, O man, who are you answering against God? Shall the thing formed say to the One forming it, Why did You make me like this? Or does not the potter have authority over the clay, out of the one lump to make one vessel to honor, and one to dishonor? But if God, desiring to demonstrate His wrath, and to make His power known, endured in much long-suffering vessels of wrath having been fitted out for destruction, and that He make known the riches of His glory on vessels of mercy which He before prepared for glory, whom He also called, not only us, of Jews, but also out of nations” (Romans 9:18-24).
Sermon on Romans 9:18