John Calvin Commentary Isaiah 6:4

"And the foundations of the thresholds shook at the voice of him that cried, and the house was filled with smoke." — Isaiah 6:4 (ASV)

And the lintels of the posts were moved. This noise was an indication that it was not a human voice that the Prophet had heard, for no mortal man has a voice so powerful as to be capable of making the lintels and posts shake. Now, the Lord intended not only to establish the authority of his voice over the Prophet, but also to confirm it to posterity for all ages, so that it might never be forgotten. Let us, therefore, know that this noise confirms even today the voice of God, so that we may tremble whenever he speaks; for if inanimate and mute creatures are moved, what ought we to do, who feel, smell, taste, and understand for no other purpose than to obey his word in a holy and reverent manner?

And the house was filled with smoke. This was the common and ordinary sign that the Lord employed with his ancient people; for we read that, whenever Moses entered into the tabernacle, smoke would usually be diffused through it in such a way that the people could not see either Moses or the tabernacle (Exodus 33:9). The smoke, therefore, that Isaiah describes was not an unusual occurrence; but in the usual way God intended to demonstrate that he would display his power in executing judgment on the people.

But it may be asked, why did God manifest his presence by this sign rather than by any other? This question may be answered in two ways. First, it was always the will of God to repress the insolence of people in pushing their inquiries about his majesty beyond what is proper; for on this point, almost all people are too rash and daring.

They wish to rise above the clouds and to penetrate into the secrets of God, while they do not see what lies at their feet. From this arises a labyrinth of errors, and when human minds have been entangled in it, they adopt false and pretended modes of worship; for when people allow themselves to adopt any false notions about God, there is nothing that they will not venture to attempt against him.

It was not without good reason, therefore, that he made use of smoke to remind people of their weakness; and yet he did not intend that they should be blind or stupid (that is, that they should have the stupidity and error that the papists disguise under the name of simplicity), but he forbids us to inquire or search beyond what he has revealed to us in his word; for, as Augustine says, “that is a learned ignorance.” Whenever, therefore, smoke of this kind is mentioned, let us recognize that it restrains us from indulging curiosity in our inquiries into the purpose of God.

Secondly, this smoke ought to strike terror, as David, when describing an angry and terrible God, says that clouds and darkness are round about him (Psalms 97:2). This also agrees well with the present passage, for he pronounces a dreadful judgment, namely, the blinding of the Jews. Others think that it indicated the burning by which he consumed the temple, but the view that I have given is more probable.