Here is an interesting and thought provoking section from John Murray on Calvin on the Sovereignty of God:
There is a twofold aspect to the will of God. And there is the disparity between the decretive and preceptive will, between the determinations of his secret counsel that certain events will come to pass and the prescriptions of his revealed will to us that we do not bring these events to pass. It cannot be gainsaid that God decretively wills what he preceptively forbids and decrectively forbids what he preceptively commands. It is precisely in this consideration that the doctrine of God’s sovereignty is focused most acutely with demands for our faith and reverence. If I am not mistaken it is at this point that the sovereignty of God makes the human mind reel as it does nowhere else in connection with this topic. It should be so. It is the sanctified understanding that reels. And it is not the mark of intelligence to allege or claim a ready resolution of the apparent contradiction with which it confronts us. How can God say: This comes to pass by my infallible foreordination and providence, and also say to us: This thou shalt not bring to pass?
Calvin was well aware of this question and he did not tone down the mystery with which it confronts us. He is constantly refuting, by appeal to Scripture, the objections which unbelief registers against this doctrine. Much of the argumentation in the last three chapters of Book I of the Institutes is concerned with it. It is of interest that the last work in which Calvin was engaged before his work was arrested by the hand of death was his exposition of the prophet Ezekiel … At Ezekiel 18:23, in dealing with the discrepancy between God’s will to the salvation of all and the election of God by which he predestinates only a fixed number to salvation, he says, “If anyone again objects, This is making God act with duplicity, the answer is ready, that God always wishes the same thing, though by different ways and in a manner inscrutable to us. Although, therefore, God’s will is simple, yet great variety is involved in it, as far as our senses are concerned. Besides it is not surprising that our eyes should be blinded by the intense light, so that we can not certainly judge how God wishes all to be saved, any yet has devoted all the reprobate to eternal destruction, and wishes them to perish. While we look now through a glass darkly, we should be content with the measure or our own intelligence.”
 Comm. ad Ezekiel 18:23; E.T. by Thomas Myers. It is more probable that the Latin verb velle, translated on three occasions above by the English term ‘wishes’, should rather be rendered ‘wills’.
The present writer [Murray] is not persuaded that we may speak of God’s will as ‘simple’, after the pattern of Calvin’s statement. There is the undeniable fact that, in regard to sin, God decretively wills what he preceptively does not will. There is the contradiction. We must maintain that it is perfectly consistent with God’s perfection that this contradiction should obtain. But it does not appear to be any resolution to say that God’s will is ‘simple’, even in the sense of the Latin term simplex.