What is the meaning of INSIDE ????

What is our cognitive undestanding of containment? Closed from all sides. What is our mind’s commonsense understanding of closedness, and thus of insideness? Firstly, there is something particular about all solids - all things. It is that anything that is solid is full-dimensional (which happens to be 3 dimensions) in its existence. That is, its surface covers all “sides” POSSIBLE, locally. Consider a foot-ball. You see its front curved surface facing you; then you rotate it, say, to the right. Then you happen to see that whatever was remaining, which was not seen earlier in the front view, is closed. The right side now is closed because your memory tells you that it is the same thing as what you saw upfront in the beginning. So the football is closed throughout. And closedness throughout leads to the concept of insideness. Anything which has a closed surface on ALL POSSIBLE sides is said to be inside that surface (3D), or loop (2D). So the key check for insideness is the ‘boundary’ or the ‘border’, ON ALL POSSIBLE SIDES.