There is a teaching of Jesus that is on the same topic as that considered in the writing of Carl Jung on the shadow. Regardless of what one thinks about the Jesus question, this is the best teaching in all of psychology regarding the first or lowest level of the soul, and this ought be accessible to those on the internet. If it is not accessible, one is inclined to say, nothing of psychology can be discussed in any way in so public a forum without doing more harm than good.
The teaching, from Matthew 7:3-5 and Luke 6:32, is that of the beam and splinter. In Matthew, it follows immediately upon the teaching of measure for measure:
Or why do you see the splinter that is in the eye of your brother, but the beam in your own eye, you do not observe? Or how will you say to your brother, allow me to cast the splinter from your eye, while also not seeing the beam in your own eye? And when you will look through to cast the beam from the eye, (then too that) of your brother
Jung calls this the shadow and the projection of the shadow, where we relate to our own sin and deficiency in projection in relation to our fellows. Two pages early in the book Aion (CW vol.9 #2) might be his best discussion of the matter. The shadow is illustrated by the difficulty humans have in arguing. Conversation that aims toward learning is simply impossible for most people, because of self interest and a certain attachment to our own thoughts. This is why, as has been said, the liberal arts and the virtues of conversation have to be cultivated. It is a great error to try to talk to people who are not capable of liberal learning and conversation, but then if one were to observe what seems to be the rule to be drawn from this, we simply have almost no one ever to whom to speak. But many hours are wasted, and a great many opportunities for learning gone into the past because we have not a clue as to how to govern ourselves, nor does it occur to the vast most that such a thing is even possible. We spend our lives, ethically speaking, fighting shadows, quarreling in opposition against defects or vices in others that may or may not truly be there, while this whole way of living or relating is from the start fruitless.
A careful translation reveals many subtleties which we have tried to render by being a bit more literal. At first, from the English, I had a teaching that one cannot remove the beam from your brother’s eye, but only the splinter, and that one must remove the beam from one’s own eye, so that if the beam were to be removed from your brother’s eye, he must cast it out himself. And this may describe what we try to do fruitlessly. This meaning may well be in there, implied by what is said, but it is not quite the primary meaning of what is being said. Dia-Blepseis, to look through, is a word used also by Plato. Combined with katanoeis, this is one key. Kata-noeis, translated “perceive,” is also observe, or consider carefully.
The phrases repeated in the translations, because they are implied, are simply not in the Greek text. What is there in the Greek instead is the immediacy of the casting of the splinter from your brother’s eye upon looking through to cast the beam from the eye, and it does not even say “your” eye, but it is now suddenly the beam and eye in general. (Then, that) of your brother.
This passage in Matthew and Luke is related to another, in Matthew 6:22(-34)
The lamp of the body is the eye. If then your eye is sound, your whole body is lit. But if your eye is bad, the whole of your body is darkened. If then the light in you is dark, how much is the darkness?…
You cannot serve God and wealth. Therefore, do not be anxious about your life…