Bears are large, powerful predators, but are also voracious omnivores, eating nuts and berries and other plant products as well as a wide variety of game. So they are sort of collecting points, taking in a wide variety of material and turning it into a powerful force.
So it makes sense in a way when Swedenborg says that bears represent the “power of external truth,” and in particular the power of the literal ideas and stories of the Bible. Like bears, those external ideas are powerful and hard to miss. And like bears, they are collecting points, the product and expression of a wide variety of thoughts and wishes.
For example, the idea that “we should be careful what we say around small children” is an external truth. Like a bear, it’s easy to see and has a powerful impact on our actions. But it’s also plain that in its simplicity it contains a wide variety of other ideas and desires: ideas about the innocence of children, the way their minds develop, the need to prepare them for life; desires to protect them and love them and see them grow to be good people.
Swedenborg says the stories of the Bible work much the same way: vivid stories that are easy to remember and often have strong, simple lessons, but also stories that contain an infinite array of ideas and desires coming from the Lord, which we can glimpse when we look for them.
Of course, these are positive images, and bears are generally frightening and destructive. This illustrates the principle that internal meanings can generally be reversed: Used in a negative way, they mean the opposite of what they mean when used in a positive way. So in most cases, bears in the Bible show the destructive power of external ideas applied without love, and the destructive power of applying the external ideas of the Bible disconnected from the love it is meant to express.
Passages from Swedenborg
Apocalypse Explained (Tansley) n. 781
[1] And his feet were as those of a bear. This signifies reasonings from natural things which are fallacies, is evident from the signification of feet, as denoting things natural (concerning which see above; n. 69, 600, 632, 666). Also from the signification of a bear, as denoting those who are in power from the natural sense of the Word, both the good and the evil, concerning which we shall speak presently. The reason why by the feet of the beast which, as to the body, was like a leopard, and as to the feet like a bear, are signified fallacies is, because by the leopard are signified reasonings which are discordant, and yet appear to be coherent (concerning which see just above, n. 780). And those reasonings, so far as they are from the ultimate Natural, which is the Sensual, are fallacies, these being signified by the feet of the bear.
[10] Such are the fallacies connected merely with faith separate from good works. There are still various others, which have reference not only to faith, but also to good works, to charity, and to the neighbour; and especially to their conjunctions with faith, which are artfully devised by the learned.
The reason why such fallacies are signified by the feet of a bear is, that by a bear are signified those who are in power from the natural sense of the Word, as well the upright as the wicked. And because by feet are signified natural things, therefore by the feet of the bear are signified the fallacies from which, by reasonings, they falsify the sense of the letter of the Word, and into which they turn the appearance of truth pertaining to that sense.
[12] The signification of the bear which David smote is similar, concerning which it is written as follows in 1 Samuel:
“David said unto Saul, Thy servant was feeding his father’s flock, and there came a lion and a bear, and took away a sheep of the flock; I went out after him, and smote him, and when he arose against me, I took hold of his beard and smote him, and slew him; thy servant smote both the lion and the bear; therefore this uncircumcised Philistine shall be as one of them, because he hath opprobriously defied the forces of the living God” (xvii. 34-37).
The reason why power was given to David to smite the lion and the bear which took away the sheep from the flock, was, that David represented the Lord as to Divine truth, by which those who belong to His church are instructed; and by the lion is signified the power of spiritual Divine truth, and in the opposite sense, as in this case, the power of infernal falsity against Divine truth; and by the bear is signified the power of natural Divine truth, and in the opposite sense, the power of falsity against that truth; but by the sheep from the flock are signified those who belong to the Lord’s church. And because these things are represented, therefore power was given to David to smite the bear and the lion, in order that by this might be represented and signified the Lord’s power of defending His own in the church by means of His Divine truth, from the falsities of evil which are from hell. That David took hold of the beard of the bear, involves a mystery, which may indeed be opened up, but can scarcely be comprehended. The beard signifies Divine truth in the ultimates, in which its very power consists. This truth even the evil, who are in falsities, do indeed confess with their mouth, but they misuse it in order to destroy it; when, however, it is taken away they have no longer any power; hence he slew the bear, and smote the lion. But this will be further explained elsewhere.
Apocalypse Revealed (Rogers) n. 573
Whose feet were like those of a bear. This symbolically means, full of misconceptions taken from the literal sense of the Word, read but not understood.
Feet symbolize the natural support which is the basis on which the heresy meant by the leopard rests and, so to speak, propels itself, and that support is the literal sense of the Word. A bear symbolizes people who read the Word but fail to understand it, so that they derive from it misconceptions.
That these are the people symbolized by bears became apparent to me from seeing bears in the spiritual world, and from seeing some people there wearing bearskins. They were all people who read the Word and did not see any doctrinal truth in it. They were also people who affirmed the appearances of truth there, resulting in misconceptions.
Some bears seen in the spiritual world are dangerous and some are not, and some also are white, but they are told apart by their heads. Bears that are not dangerous have heads like those of calves or sheep.
True Christian Religion 223
This correspondence is the reason why forty-two youths were torn apart by two she-bears for calling Elisha bald (2 Kings 2:23, 24). Elisha represented the church’s teaching from the Word. The she-bears stood for the power of truth on the outermost levels.
The power of divine truth or of the Word exists in its literal meaning because at that level the Word is complete, and people and angels of each of the Lord’s kingdoms share in it together.
Apocalypse Revealed 47
For that reason as well, forty-two of the boys who called Elisha a baldhead were torn apart by two she-bears. Like Elijah, Elisha represented the Lord in relation to the Word. A baldhead symbolizes the Word without its outmost expression, which, as said, is its literal sense, and she-bears symbolize this sense of the Word divorced from its inner meaning. Those who so divorce it, moreover, appear in the spiritual world as bears, though only at a distance. It is apparent from this why what happened to the boys happened as it did.