Unless we are possessed of an unusual degree of self-awareness we shall never see through our projections but must always succumb to them, because the mind in its natural state presupposes the existence of such projections. It is the natural and given thing for unconscious contents to be projected. In a comparatively primitive person this creates that characteristic relationship to the object that Levy-Bruhl has fittingly called "mystic identity", or "participation mistique". Thus every normal person of our time who is not reflective beyond the average, is bound to his environment by a whole system of projections
(Jung, CW 8, par 507)

Just as we tend to assume that the world is as we see it, we naively suppose that people are as we imagine them to be. In this latter case, unfortunately, there is no scientific test that would prove the discrepancy between perception and reality. Although the possibility of gross deception is infinitely greater here than in our perception of the physical world, we still go on naively projecting our own psychology into our fellow human beings. In this way everyone creates for himself a series of more or less imaginary relationships based entirely on projection.
(Jung, CW 8, par 507)