In this fourth chapter of the Book of Jonah, (Jonah 4), the prophet Jonah has a strange reaction to his success. He's angry, and sulky. He thinks he knows better than God does. What is this story about?

Rev. George McCurdy, in his exegesis of this chapter, offers a summary in his Study Guide for the Book of Jonah, which is available for free as a .pdf, for your use. Below, we've excerpted part of his summary, and edited it for use in this context.

The people of the Jewish church in Jonah's time didn't want to reconsider their belief in their "most-favored-nation status." They challenged the Lord. They couldn't understand why He wanted to save their enemies in Nineveh.

Despite the hard lessons in chapters 1 and 2, and his success as described in chapter 3, Jonah still thought he knew better than the Lord. He thought that God was being too soft and loving -- too forgiving -- and that He needed to come around to Jonah’s tougher view.

Jonah got so angry and vengeful that he preferred to die rather than approve of the Lord’s way to save the Ninevites. His self-love wanted shade -- protection for its concepts. The Lord needed to bring such thinking to an end; the worm brought about death to the gourd from within. The Lord then sent a vehement east wind, that represents a blowing away of the stagnant thinking of the church.

The Lord's heavenly sun shone upon Jonah, but he felt faint. Here, Jonah's insistence on his own troubling view of things made him uncomfortable with the Lord’s view. The Divine guidance offered him a way to learn to enjoy the success of his neighbors as his own, but he wouldn't take it.

For us, then -- what? This story is telling us that we can't just keep the truths of the Word for ourselves; we have to go to Nineveh and share them. And then, if people start to hear them, and use them to turn their lives around, we can't allow ourselves to get resentful that the Lord accepts their repentance and forgives them. It's a very human reaction; think of the disciples vying to be first in the Lord's command structure (Luke 9:46), or the brother of the prodigal son (Luke 15:28-29), or the workers in the vineyard who had worked all day for a denarius (Matthew 20:10-12). But... it's not a good reaction. The Lord doesn't admire it in Jonah, and doesn't admire it when it crops up in our minds, either.

Rev. Martin Pennington recommends several explanatory passages from Swedenborg's theological writings:

"Shade or shadow means the perception of good and truth lies in obscurity." (Arcana Coelestia 2367)

"A vine is spiritual good (the spiritual church)". (Arcana Coelestia 217)

"A worm represents falsity gnawing away and tormenting one." (Arcana Coelestia 8481)

"'And the sun grew hot' in the contrary sense means self-love and love of the world." (Arcana Coelestia 8487)

And... here's a link to an interesting (audio) sermon on this chapter, by Rev. Todd Beiswenger.

8481. 'And it bred worms' means that it was consequently something foul. This is clear from the meaning of 'breeding worms' as producing something foul; for worms are born from what is foul and putrid. Falsity arising from evil, present in good originating in the proprium or self, is compared to a worm because they are of a similar nature to each other; for falsity gnaws away and so torments. There are two entities constituting hell, just as there are two constituting heaven. The two constituting heaven are goodness and truth, and the two constituting hell are evil and falsity. Consequently the two in heaven are what make the happiness there, and the two in hell are what cause the torment there. The torment in hell caused by falsity is compared to a worm, and the torment caused by evil there is compared to fire. This is why it says in Isaiah,

As the new heavens and the new earth which I am about to make will stand before Me, so will your seed and your name stand. At length it will happen from month to month, and from sabbath to sabbath, that they will stand before Me. They will go forth from there and will see the dead bodies of the men transgressing against Me For their worm will not die, and their fire will not be quenched. And they will be loathsome to all flesh. Isaiah 66:22-24.

Similar words were used by the Lord, in Mark,

Where their worm will not die, and the fire will not be quenched. Mark 9:44, 46, 48.

This refers to Gehenna or hell. The foulness of falsity is compared to a worm also in Moses,

You will plant and dress vineyards, but not drink wine nor gather [the fruit]; for the worm will eat it. Deuteronomy 28:39.

'Wine' stands for truth springing from good, and in the contrary sense for falsity arising from evil, 6377.