John Calvin Commentary Isaiah 29:8

"And it shall be as when a hungry man dreameth, and, behold, he eateth; but he awaketh, and his soul is empty: or as when a thirsty man dreameth, and, behold, he drinketh; but he awaketh, and, behold, he is faint, and his soul hath appetite: so shall the multitude of all the nations be, that fight against mount Zion." — Isaiah 29:8 (ASV)

It shall be therefore as when a hungry man dreameth. He compares the Jews to “hungry men,” who are indeed asleep, but whose empty stomach craves food; for it is natural for men to dream about food and entertainments when they lack them.

Thus, while the Jews were awake, they were like “hungry men.” The Lord continually warned them by his prophets and invited them to the divine feasts of the word; but they despised those feasts and preferred to take complete refuge in their vices and to fall asleep in them, rather than to fully partake of those sacred feasts.

Accordingly, while they quieted their consciences, they imagined that they had an abundance of all things and that they were free from every inconvenience. Isaiah declares that they greatly resemble this “dream” and airy “vision;” for, when they have been aroused by a sudden calamity, they will feel how empty and insubstantial those “dreams and visions” were, and how false and delusive was the opinion they had formed that they enjoyed abundance.

Just as “hungry men” who have had such dreams are made weaker by them, so the people, who had been falsely persuaded that everything was going on well with them, will endure much greater uneasiness than if they had never cherished such a thought in their minds but had instead been aware of their poverty and nakedness.

So shall be the multitude. At first glance, the expression appears to be harsh when he says, “The multitude of those who fight against Ariel shall be as a dream;” but it should be explained in this manner: — “When the Jews, through false hope, will promise themselves deliverance, as if the enemies would be driven far away, they will quickly feel that they had been deceived, in the same way that a person whom hunger leads to dream that he is feasting luxuriously, as soon as he awakens, feels that his hunger is keener than before.” I see nothing here, therefore, that is suited to offer consolation, for the Prophet pursues the same subject and exclaims against the scorn and rebellion of the Jews, on whom the Prophet could make no impression by exhortation or threats.