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.

4899. 'Behold, I sent this kid' means it is enough that a pledge exists. This is clear from the meaning of 'a kid of the she-goats' as a pledge of conjugial love or of one assuring a joining together, dealt with in 4871, in this case simply a pledge since the kid was not accepted for the reason given already, that nothing of marriage existed. And because it was not for that reason accepted, 'you did not find her' therefore means even if nothing of marriage exists. This also ensues from the lack of interest referred to in 4897. Any further explanation of these matters is abandoned here for the reason given above in 4893, namely that it would enter the unlit parts of the understanding, and any ideas entering those unlit parts enter where no belief is present. For example the idea that something of marriage must be present if the Church is to exist; that is to say, the idea that some marriage must exist between truth and good. Also, the idea that what is internal must be present within what is external, and that without this and the previous requirement no Church at all exists. It is the exact nature of these realities within the Jewish Church that forms the subject here in the internal sense. That is to say, this sense deals with how, so far as that nation itself was concerned, nothing internal within what was external existed, but so far as their actual statutes and laws were concerned, something internal existed within these.

[2] Does anyone at the present day believe anything other than this, that the Church existed among the Jewish nation, indeed that this nation was chosen and loved in preference to all others, the chief reasons for such belief being that so many and such great miracles were performed among that nation, so many prophets were sent to it, and also the Word existed among it? Yet that nation possessed nothing at all of the Church within it, for no charity existed there; of what genuine charity was they were completely unaware. Nor did any faith in the Lord exist there. It knew that He was to make His coming, but believed that this was to set it above all people throughout the world. As this did not happen it rejected Him altogether. Of His heavenly kingdom it had no wish to know anything at all. The things which constitute the internal features of the Church were not even acknowledged in what that nation taught, let alone in its life. From all this one can only conclude that no Church at all existed within that nation.

[3] It is one thing for the Church to exist among a nation, and another for the Church to exist within a nation. For example, the Christian Church exists among those who have the Word and use doctrine to preach about the Lord. Yet no Church at all exists within them if no marriage of good and truth is present in them, that is, if charity towards the neighbour and faith rooted in this is not present in them, thus if the internal features of the Church are not present within the external ones. Those with whom solely external features separated from internal are present do not have the Church within them. Nor do those with whom faith separated from charity is present have the Church within them. Neither do those who acknowledge the Lord in their teachings but not in life have the Church within them. From this example it is evident that it is one thing for the Church to exist among a nation, and another for it to do so within a nation.

[4] The subject in the internal sense of this chapter is the Church among the Jewish nation and within that nation. The essential nature of the Church existing among that nation is described by Tamar's being joined to Judah under the pretext that the duty of a near kinsman was being performed, while the essential nature of the Church existing within that nation is described by Judah's being joined to Tamar as a prostitute. But a more detailed explanation of these matters is abandoned here for the reason given above, that it would enter, as stated, the unlit parts of the understanding. The accommodation of these matters in the unlit parts of the understanding is evident from the fact that at the present day scarcely anyone knows what the internal aspect of the Church is. This internal aspect is essentially charity towards the neighbour present within the intentions of a person's will, and from these in his actions, and from these again in faith within his perception; yet who knows this? When this is unknown, more so when it is denied, as is done by people who make faith without the works of charity the bringer of salvation, how unlit must those parts of the mind be, into which the ideas pass that are stated here in the internal sense about the joining of the internal aspect to the external aspect of the Church among the Jewish nation and within that nation? Those who have no knowledge of the existence of that internal and so essential aspect of the Church stand far removed from the first step towards understanding such ideas, and as a consequence from the countless, indescribable things existing in heaven, where realities connected with love to the Lord and love towards the neighbour constitute every trace of life, and consequently every trace of wisdom and intelligence.