We think of insides as being the insides of outsides - for it is only outsides that we know, and even what we speak of as insides are themselves only outsides within other outsides.
If we understood, we should see things the other way round, for the within is nearer reality than the without. Everything we know should be the without of a within, the external appearance of something real and unseen within, 'behind' or 'beneath' it.
This is an aspect of the realisation that negative, not positive, is fundamental.
Moreover we think of ourselves as outsides and 'inside' is to us either an organ (itself another outside) or something mental. There we approach the truth - but like a moth trying to light on a candle-flame.
If we firmly transvalued our values and thought of our selves as withins, and only as withins - withouts being merely symbols thereof - we should be at least on the road that leads in the direction of understanding.