In the third chapter of the Book of Jonah, Jonah finally reaches Nineveh, and starts preaching repentance and reformation to the people there. And... they listen! Even the King of Assyria listens!

The inner meaning of the story is pretty close to the surface here, and there's important symbolism. Swedenborg summarizes the chapter's meaning in this one sentence:

"The nations, hearing from the Word of God about their sins, and that they would perish, were converted after repenting, and were heard by the Lord, and saved." (The Inner Meaning of the Prophets and Psalms 213)

Rev. George McCurdy, in his exegesis of this chapter, offers this summary:

The great city of Nineveh has many spiritual representations. The world saw Nineveh as a mighty nation, but in the eyes of the Lord, it represented the shallowness and weakness (death) of false doctrines, contrived beliefs confirmed by the proprium (self love), the fallacies of the senses, and the unenlightened understanding that spawns spiritual ignorance.

The Lord’s mercy and love for all prompted Him not only to send His message to Nineveh, but to ensure that it would be preserved for eternity. Jonah’s call to "arise and go" preach to Nineveh is a call for spiritual renewal. It is a call for repentance. The fasting, sackcloth, and ashes symbolize a call to be aware that "where there is no truth, there is no church."

Where the Word is closed, and not loved, there is a loss of conjunction with the Divine resources. The fasting of man and beast symbolizes a need for the spiritual and natural appetites to come to the Lord for that "bread which comes down from heaven." The Ninevites giving up their natural food and drink represents their turning away from "as-of-self" concepts and reminds all who read and hear the Word of the Lord to rely on heavenly manna.

"Why do you spend money for what is not bread, and your wages for what does not satisfy? Listen carefully to Me and eat what is good, and let your soul delight itself in abundance…" (Isaiah 55:2)

The king sitting in ashes and mourning represents a sorrowful attitude toward "the remains of the fire of self-love." Repentance involves self-examination, making oneself guilty for the sins and evils committed, asking the Lord for His help, and desiring to attain a new life.

As we mull over this concept, think about the Lord’s preaching on earth. As He went about His mission, He often used these words: "You have heard it said of old… but I say unto you…" Putting aside human traditions and taking on the Lord’s teachings is an ongoing effort. Jonah was told to preach the words of the Lord. He was not to make things up from his memory. He was to be a true and faithful prophet of the Lord’s ways.

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

Rev. Martin Pennington suggests two explanatory passages from Swedenborg's theological writings:

"Forty days means a period of temptation combats or severe change." (Arcana Coelestia 730)

"A fast represents those who are in a state of unhappiness when good is no longer joined to the truths." (Arcana Coelestia 9182[10])

Other references of interest listed by Rev. McCurdy include:

"As ‘forty’ signified what is full or complete… forty signifies what is complete in respect to instruction and influx… for this reason it was said by Jonah to the Ninevites that ‘the city would be overthrown after forty days" (Jonah 3:4) (Arcana Coelestia 9437[2])

"By being clothed in sackcloth is signified mourning on account of the vastated truth in the church; for garments signify truths; and therefore, to be clothed in sackcloth, which is not a garment, signifies mourning that there is no truth; and where there is no truth, there is no church." Jonah 3:5-6 is cited. (Apocalypse Revealed 492)

"…the rite of putting sackcloth on the loins to testify…mourning may be seen from the historic and prophetic parts of the Word, as in… Jonah 3:5-8… for a sign representative of mourning over the evil on account of which Nineveh was to perish; thus over destroyed good." (Arcana Coelestia 4779[2])

"From the signification of garments it is also manifest why they rent their garments, when any one spoke against the Divine truth of the Word… and why, on account of transgressions against Divine truths, they put off their garments, and put on sackcloth." Jonah 3:5, 6, and 8 are cited. (Apocalypse Revealed 166)

"That ‘ashes’ denote falsity, may be confirmed from passages where another word for ‘ashes (cinis)’ is used, for these ashes have a like origin…" Jonah 3:6 is cited. (Arcana Coelestia 7520)

"…by ‘ashes’ in the opposite sense, namely, what is condemned that remains after the burning from the fire of self love. This is signified by ‘the ashes’ which they carried on the head, and in which they rolled themselves when bewailing their sins." Jonah 3:6 is cited. (Arcana Coelestia 9723)

"In the spiritual sense by kings those who are in truths are signified, by the great ones those who are in goods, by the rich those that are in the knowledge of good, by the mighty they that are in erudition, by servants they that are in such things from others, and thus from memory, and by freemen they that are in such things from themselves…" Jonah 3:7 is cited. (Apocalypse Revealed 337)

"The interior good and also the interior evil…are signified by ‘man,’ are those which are of the intention or end, for the intention or end is the inmost of man; but the exterior good and also the exterior evil which are signified by ‘beast,’ are those which are of the thought, and of the consequent action when nothing stands in the way…By ‘beast,’…in respect to the external or natural man, a man is nothing else than a beast, for he takes delight in the like cupidities and pleasures, as also in the like appetites and sense…Therefore… from a holy rite it was commanded by the king of Nineveh, that both man and beast were to fast, and were to be covered with sackcloth (Jonah 3:7, 8)." (Arcana Coelestia 7523)

"… in the spiritual world a man’s affections appear at a distance like beasts… and beasts, viewed in themselves, are nothing but forms of natural affections… By man and beasts together is signified man as to spiritual and natural affection, in the following passages… Jonah 3:7, 8…" (Apocalypse Revealed 567)

"Here ‘webs’ and ‘garments’ are predicated of things of the understanding, that is, of the thought; ‘iniquity’ and ‘violence,’ of things of the will, that is, of works. In Jonah 3:8… the ‘evil way’ is predicated of falsities, which are of the understanding; and ‘violence,’ which are of the will." (Arcana Coelestia 623[2])

"…the ‘wrath of anger’ is attributed to Jehovah, and consequently ‘repentance.’" (Arcana Coelestia 588[2])

"…the Word is such in the sense of the letter, it may be evident that it cannot be understood without doctrine. But let examples illustrate this. It is said that Jehovah repenteth (Jonah 3:9; 4:2), and it is also said that Jehovah repenteth not (Num. 23:19…): without doctrine these statements do not agree." (Teachings Regarding the Sacred Scripture 51)

"In these passages (Jonah 3:9,10) Jehovah is said to have ‘repented,’ when yet it cannot be that He repents, because He knows all things before He does them; from which it is evident that by ‘repenting’ is signified mercy." (Arcana Coelestia 10441[2-4])

Finally, here's a link to Rev. McCurdy's study guide for the Book of Jonah, which is available for free as a .pdf, for your use.

606. 13:17 So that no one can buy or sell if he does not have the mark or the name of the beast, or the number of its name. This symbolically means that no one is allowed to teach from the Word, or consequently to be inaugurated into the priesthood, to be accorded the badge of the teaching office, to be granted the doctor's cap, and called orthodox, but one who acknowledges that doctrine and swears to a belief in it and love for it, and to such as is in conformity with it, or such as does not conflict with it.

To buy and to sell mean, symbolically, to acquire concepts, in this case concepts having to do with that doctrine, and to teach them, as shown below. The mark of the beast symbolizes an acknowledgment that one is a Reformed Christian, and a confession that one is such (no. 605). The name of the beast symbolizes the character of the doctrine, a name symbolizing character (nos. 81, 122, 165, 584), and the beast symbolizing the doctrine accepted by the laity, thus by the general populace (no. 567). Moreover, because the verse says "or the name of the beast," it symbolizes its character or such as is in conformity with it. A number symbolizes the character of a thing (no. 448), and because the verse says "or the number of its name," it symbolizes the character of the doctrine or such as does not conflict with it.

It is stated so, because the doctrine symbolized by the dragon and its beast is not the same throughout the kingdoms in which Reformed Protestants are found, though it is the same in respect to this postulate or principal tenet of the doctrine, that faith justifies and saves apart from works of the law.

[2] That to buy and to sell mean, symbolically, to acquire concepts for oneself and to teach them, and so likewise to market, trade, and make a profit, is clear from the following passages:

Everyone who thirsts, come to the waters; and you who have no money, come, buy and eat. Yes, come, buy wine and milk without money... (Isaiah 55:1)

You have sold yourselves for nothing; (therefore) you shall not be redeemed with money. (Isaiah 52:3)

With your wisdom and your understanding you have gained riches for yourself...; by your great wisdom in your trading you have increased your riches... (Ezekiel 28:4-5)

Since Tyre symbolized the church in respect to its concepts of goodness and truth, therefore we are told the following concerning Tyre:

All the ships of the sea... were... to market your merchandise... Tarshish was your trader...(in) silver... Javan, Tubal, and Meshech were your merchants. With human life... they carried on your trading... Syria was your trader... with chrysoprase... Your riches, your wares, and your merchandise..., ...those carrying on your trade..., will fall into the midst of the seas on the day of your ruin. (Ezekiel 27:9, 12-13, 16, 27)

Wail, you ships of Tarshish! For (Tyre) is laid waste..., whose merchants are princes, and whose traders are the honored of the earth? (Isaiah 23:1-8)

Trading has the same meaning in the Lord's parable about a man traveling to a far country, who gave his servants talents to trade with and make a profit (Matthew 25:14-30). In another parable about a man who gave his servants ten minas for them to do business with (Luke 19:12-26). In the parable regarding a treasure hidden in a field, which a man found and hid, who sold all that he had and bought the field (Matthew 13:44). And in the one about a man seeking beautiful pearls, who, when he had found one precious one, sold all that he had and bought it (Matthew 13:45-46).

Such have they become..., your merchants from your youth; they shall wander each one from his region, not saving you. (Isaiah 47:15)

And so on elsewhere.