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.

3820. 'And Leah's eyes were weak' means that the affection for external truth is weak so far as the understanding of it is concerned. This is clear from the representation of 'Leah' as the affection for external truth, dealt with in 3793, and immediately above in 3819; from the meaning of 'the eyes' as the understanding, dealt with in 2701; and from the meaning of 'weak' as its being such in comparison with the affection for internal truth. The fact that affections for external truth are weak so far as the understanding of it is concerned, or what amounts to the same, so far as people governed by those affections are concerned, becomes clear from external - that is, general - ideas which have not yet been filled in with their particular details. They are feeble and shaky ideas, which so to speak allow themselves to be carried along by every puff of wind, that is, to be won over to every opinion. But when those same ideas have been filled in with their particular details they emerge as firm and steadfast ideas, for they then possess the essence and form meant by 'beautiful in form and beautiful in appearance' as Rachel was, who represents the affections for interior truth.

[2] Let the following example show what is meant by external truths and the affections for them, and what by internal truths and the affections for these, and the fact that the former are 'weak eyed' in comparison with the latter, which are 'beautiful in form and appearance': Those governed by external truths know no more than the general truth that good should be done to the poor. They do not know how to tell who are truly the poor, let alone know that in the Word the expression 'the poor' is used to mean those who are so spiritually. Consequently they do good to bad persons and to good ones alike, without realizing that doing good to bad people is doing bad to good, for the bad are then given the opportunity to do bad to those who are good. This is why people possessing this kind of simple zeal are infested so strongly by the crafty and deceitful. But those governed by internal truths know who the poor are, tell one poor person from another, and do good to each according to his individual character.

[3] Take another example. Those governed by external truths know no more than the general truth that the neighbour ought to be loved. They as a consequence believe that every individual is the neighbour in the same degree, and so every individual ought to be embraced with the same love. Believing this, they allow themselves to be misguided. Those however who are governed by internal truths know which degree of the neighbour each person belongs to and that any one person is the neighbour in a different degree from another. Consequently they are aware of countless things which those governed by external truths do not know. They do not therefore allow themselves to be led astray by the mere name of neighbour, or to do what is evil by performing that good which the name alone persuades them to do.

[4] Take yet another example. Those governed by external truths alone imagine that the learned will shine like stars in the next life, and that all who have worked in the Lord's vineyard will have a greater reward than others. But those governed by internal truths know the expressions 'learned', 'wise', and 'intelligent' are used to mean those in whom good is present, whether they possess any human wisdom and intelligence or not, and that it is these who will shine like stars. They also know that those who work in the vineyard receive a reward, each according to the affection for good and truth which motivated him in his work, and that those who work from selfish and worldly motives, that is, from self-aggrandizement and enrichment as motives, have their reward during their lifetime, but in the next life their lot is with the evil there, Matthew 7:22-23.

From these examples it is evident how weak in understanding those people are who are governed by external truths alone, and that internal truths are what give them essence and form, and also what determine the character of the good with them. Nevertheless people governed by external truths, and at the same time when in the world simple good was present in them, receive internal truths and resulting wisdom in the next life, for by virtue of that simple good they are in the right state and have the capacity to receive them.