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.

5280. 'And the abundance of corn in the land will not be known' means that no discernment at all regarding the truth present previously will exist there. This is clear from the meaning of 'being known' as being discerned; from the meaning of 'the abundance of corn' as truth that has been multiplied, dealt with above; in 5276, 5278; and from the meaning of 'the land', in this case the land of Egypt, as the natural mind, also dealt with above, in 5276, 5278, 5279. From these meanings it is evident that 'the abundance of corn in the land will not be known means that no discernment at all regarding the truth present previously will exist in the natural.

[2] This verse deals with the final state of desolation, when despair, which comes immediately before regeneration, is experienced; and this being the matter dealt with in this verse, something must be said about the nature of it. Everyone has to be reformed, and to be born anew or regenerated, so that he may enter heaven, No one, unless he is born again, can see the kingdom of God. John 3:3, 5-6.

The human being is born into sin which has increased as it has come down in a long line of descent from ancestors, grandparents, and parents; it has become hereditary and so has been handed down to offspring. At birth a person is born into so many inherited evils which have gradually increased, as described, that he is nothing but sin; therefore unless he undergoes regeneration he remains wholly immersed in sin. But to be regenerated, he must first undergo reformation, which is effected by means of the truths of faith; for he must learn from the Word, and from teaching drawn from it, what good is. Items of knowledge regarding what is good that have been acquired from the Word - that is, from teaching drawn from there - are called the truths of faith; for all truths of faith well up out of good and flow in the direction of good, good being the end they have in view.

[3] This state comes first and is called the state of reformation. Most people within the Church are introduced into it during the period from young childhood through to adolescence, though few are regenerated because most people within the Church learn the truths of faith - or religious knowledge about what is good - for the sake of reputation and position and for the sake of material gain. Since therefore the truths of faith have been introduced through his love of these things, a person cannot be born anew or be regenerated until that love has been removed. To enable such love to be removed that person is launched into a state of temptation, which takes place in the following way: His love of reputation, position, and material gain is activated by the hellish crew, for that crew's desire is to live immersed in the love of those things. But at the same time angels activate affections for what is true and good which were implanted in the state of innocence during early childhood and then stored away interiorly and preserved there for this particular purpose. As a result conflict between evil spirits and angels takes place, and this conflict taking place within a person is experienced by him as temptation. And because the action at this time involves truths and forms of good, the actual truths which were instilled initially are so to speak banished by the falsities infused by the evil spirits - so banished that they are not seen - dealt with above in 5268-5270. And as the person allows himself at this time to be regenerated, the Lord introduces through an internal route the light of truth radiated from good in the natural, in which light the truths are restored there in their proper order.

[4] This is what happens to a person who is being regenerated, but few at the present day are permitted to enter that regenerative state. So far as they allow it to happen, all people, it is true, start to be reformed through the instruction they receive in the truths and forms of good that belong to spiritual life; but as soon as they reach adolescent years they allow the world to distract them. So they turn away into those parts where hellish spirits are, who gradually alienate these people from heaven; the spirits alienate them so completely that they scarcely believe any longer in the existence of heaven. Consequently those people cannot be launched into any spiritual temptation; for if they were they would go under instantly, in which case their latter state would be worse than their former one, Matthew 12:45. From all this one may see the nature of what the internal sense contains here, namely the state of reformation and the state of regeneration. This particular verse however describes the final state in temptation, which is a state of despair - this state being dealt with immediately above in 5279.