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.

9393. 'And Moses took half of the blood' means Divine Truth which has become a matter of life and of worship. This is clear from the meaning of 'the blood' as Divine Truth emanating from the Lord, dealt with in 4735, 6978, 7317, 7326, 7850, 9127. The reason why it is Divine Truth which has become a matter of life and of worship is that it was the blood which Moses sprinkled over the people, verse 8, and this blood means Divine Truth which a person has accepted, thus that which has become a matter of life and of worship; for that Truth is said to have been accepted by a person which becomes a matter of life and so of worship. And it becomes a matter of life and worship when the person has an affection for it or loves it, or what amounts to the same thing, when he wills it, and - in willing it, and so in loving and having an affection for it - does it. Till then it is indeed present with him in his memory, and is at times called forth from there and comes before his inward sight or understanding, from where it passes back into his memory. However, as long as God's truth goes no deeper than this, though it resides with the person it has not been implanted in his life and will; for a person's life consists in his will. Therefore when truth is called forth from the memory into the understanding, then passes from the understanding into the will, and goes out from the will into action, that truth becomes part of the person's life and is called good. All this shows what is meant by Divine Truth which has become a matter of life. The situation is the same with truth which becomes part of worship. Worship springing from truth which does no more than cling in the memory and make its appearance from there in the understanding is not worship. But worship springing from truth that goes out from the will, and so from affection and love, is worship. In the Word this worship is called worship of the heart, but the other, worship of the lips alone.

[2] It has indeed been shown already in the places referred to above that 'blood' means Divine Truth emanating from the Lord. Nevertheless since the majority belonging to the Church at the present day take the blood in the Holy Supper to mean nothing other than the Lord's blood that was shed on the Cross, and in a more general sense His whole Passion of the Cross, let something further be stated briefly to show that blood is not what is meant there but Divine Truth emanating from the Lord. The reason why this is unknown within the Church is that nothing whatever is known at the present day about correspondences, nor consequently about the internal sense of the Word, the sense understood by angels when someone in the world reads the Word.

[3] It becomes clear from many places in the Word that 'blood' does not mean blood but God's truth, and plainly so from the following in Ezekiel,

Say to every bird of the air and to every wild animal of the field, Assemble and come, gather yourselves from all around to My sacrifice which I am sacrificing for you, so that you may eat flesh and drink blood. You will eat the flesh of the mighty, and drink the blood of the princes of the earth. You will eat fat till you are glutted, and drink blood till you are drunk, from My sacrifice which I will sacrifice for you. You will be glutted at My table with horse and chariot, and with every man of war. Thus will I set My glory among the nations. Ezekiel 39:17-21.

It is plainly evident that 'blood' is not used here to mean blood, for it says that they were going to drink the blood of the princes of the earth, and the blood from the sacrifice, till they were drunk, when yet drinking blood, especially the blood of princes, is something abominable and was forbidden to the children of Israel on pain of death, Leviticus 3:17; 7:26; Leviticus 17:1-end; Deuteronomy 12:16-25; 15:23. It also says that they were going to be glutted with horse, chariot, and every man of war. Anyone therefore who does not know that 'blood' means Divine Truth, 'princes' leading truths, 'sacrifice' the things that belong to worship, 'horse' the understanding of truth, 'chariot' doctrinal teachings, and 'man of war' truth engaged in conflict against falsity is bound to be bemused by each of the words used in this passage.

[4] His response would be the same to the Lord's words in John,

Jesus said, Truly, truly, I say to you, Unless you eat the flesh of the Son of Man and drink His blood, you will have no life in you. Whoever eats My flesh and drinks My blood has eternal life, and I will raise Him up at the last day. My flesh is truly food, and My blood is truly drink. He who eats My flesh and drinks My blood abides in Me, and I in him. John 6:53-56.

But see what has been shown already regarding these words, in 4735, 6978, 7317, 7326, 7850, 9127. The fact that flesh corresponds to good, as does bread, and that blood corresponds to truth, as does wine, has been told me very many times from heaven. I have likewise been told that angels understand the Word solely according to correspondences, and that as a result of this mankind is joined by means of the Word to heaven, and through heaven to the Lord.

[5] And in like manner I have been told that the Holy Supper was established by the Lord to be the means by which all things of heaven, that is, all things which are the Lord's, might be joined to members of the Church. For in the Holy Supper the flesh or bread is the Divine Good of the Lord's Divine Love towards the whole human race, and a person's love in return to the Lord, while the blood or wine is the Divine Truth emanating from the Divine Good of the Lord's Divine Love, and in turn the person's acceptance of it. In heaven, furthermore, eating and drinking those gifts implies making them one's own and joining them together. But see what has been shown already regarding these matters in 2165, 2177, 3464, 4211, 4217, 4581, 4735, 5915, 6789, 7850, 9323.