'Skins' or 'hides' signify external things, because the hide is the outermost organ of an animal where its interiors extend, the same as with a person's dermis or skin. 'Skin' corresponds to truth or to falsity in the extremes. See Arcana Coelestia 1835, 10036, and Apocalypse Explained 386. 'Skin,' as in Job 19:26, means the natural degree a person has with him after death.

In Exodus 22:27, this signifies things that are relatively external. (Arcana Coelestia 9215)

In Exodus 34:29, this signifies the internal of the Word shining from the external. (Arcana Coelestia 10691)

In Job 19:20, this signifies being not entirely in falsities. (Apocalypse Explained 556[11])

In Jeremiah 13:23, this signifies that evil cannot change its nature. (Apocalypse Explained 780[5])

In Genesis 3:21, this signifies that the Lord instructed them in spiritual and natural good. (Arcana Coelestia 292)

In Genesis 27:16, this signifies the external truths of domestic good. (Arcana Coelestia 3540)

5096. 'Who were bound in the prison house' means which were among falsities. This is clear from the meaning of 'being bound in the prison-house' as being among falsities, dealt with in 4958, 5037, 5038, 5085. Those who are engrossed in falsities, more so those steeped in evils, are called 'the bound" and 'in prison', not because they are held in any physical bonds but because they are not in freedom; for people who are not in freedom are inwardly in bonds. Indeed once they subscribe to falsity they no longer have any freedom to choose or receive what is true; and those who subscribe heavily to it do not have any freedom even to see it, let alone acknowledge it and believe it, because they are quite convinced that what is false is true and what is true is false. That conviction is so powerful in them that it removes all freedom to think anything different, and is so strong that it holds their actual thought in bonds, in prison so to speak. This has been made clear to me from considerable experience among those in the next life who have become quite convinced of falsity by harbouring ideas that serve to prove to it. They are the kind of people who do not entertain any truths at all but turn or drive these away, doing so with a degree of ruthlessness which matches the intensity of their conviction. This is primarily so when such falsity is the product of evil, that is, when evil causes them to be convinced of it. These are the ones who are meant in the Lord's parable in Matthew,

Other seeds fell on the hard path, and the birds came and devoured them. Matthew 13:4.

'Seeds' means Divine truths, 'hard rock' conviction, and 'birds' false assumptions.

[2] People like these are not even aware that they are in bonds or in prison, for they are full of affection for their falsity, loving it because of the evil which produces it. This leads them to think that they are in freedom, since everything they have an affection for or love seems to make them feel free. But those who have not really subscribed to falsity, that is, who have not become convinced of it, entertain truths easily. They see them, choose them, and are full of affection for them, after which they look down on falsities so to speak, and then see how those convinced of falsity have come to be in bonds. Having such freedom they are able in their contemplation and thought to roam so to speak through the whole of heaven in search of countless truths. But nobody can have this freedom except one who is governed by good; for it is by virtue of good that he is in heaven and by virtue of good that truths are seen there.