'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)

387. And with death, signifies the consequent extinction of spiritual life. This is evident from the signification of "death," as being the extinction of spiritual life (See above, n. 78, 186). That this is what "death" here signifies is evident from the series of things in the internal sense; for it is said that "there was given unto them power to kill with sword, with famine, and with death;" and "sword" signifies falsity destroying truth, "famine" the deprivation of the knowledges of truth and good; thence "death" signifies the extinction of spiritual life; for where falsity reigns, and where there are no knowledges of truth and good, there is no spiritual life, for spiritual life is acquired by means of the knowledges of truth and good applied to the uses of life. For man is born into all evil and falsity from evil; he is therefore born also into an entire ignorance of all spiritual knowledges; therefore in order that he may be led away from the evils and consequent falsities into which he is born, and be led into the life of heaven and be saved, he must needs acquire the knowledges of truth and good, by means of which he can be led into spiritual life and become spiritual. From this series of things in the internal sense it is evident that "death" here signifies the extinction of spiritual life; this is meant, too, by spiritual death.