I've been thinking about dimensions lately. I'm generally trying to improve my understanding by thinking about points, or restricting my thought experiments to one spatial and one temporal dimension. I do think it helps to leave a single temporal dimension intact, simply because it's so ingrained into my natural thought processes that one should be there. Still, it's early days yet. However, I did come across a mildly interesting byproduct.
So I'm in this large open space, with pretty much nothing else in it - just a featureless plain. I come across a 3 dimensional universe - that's 2 spacial dimensions and 1 temporal dimension, compared to the 3 spacial dimensions and 1 temporal dimension I currently seem to exist in. This new universe is rich and complex and has intelligent life, but from my point of view seems restricted to a 2-dimensional plane. Moreover, even the apparently intelligent inhabitants of this universe seem to have no way of detected my 'additional' dimension.
I can see them, but they can't see me. In fact, I can see their world in a way that they can't: walls and other obstacles form no obstruction to my vision, as their entire 'flat' universe is laid out as an open page to my sight. There's a potential restriction here, as all of their universe (certainly artificial signs and suchlike) are designed for visibility only within their 2-D plane, but somehow I have overcome this problem and can make sense of things pretty well. I can only be detected if I choose to step forward into the 2-D plane - even then, only the tiny fraction of my physical form which exists in that plane will be sensible to them, and may take an apparently bizarre shape. It's hard to see how they can ever detect me or anything in my 'additional' dimension without its cooperation in moving into their realm - it may be possible, but the fact is that physically these beings are at a distinct disadvantage to me and other inhabitants of my universe.
Can I injure them? Possibly an attempt to strike directly from my additional dimension would go right through them, as in that dimension they have no 'depth' as such. I can certainly attack them within their own plane, with a tremendous advantage of surprise - I can appear anywhere at any time, I have a full knowledge of their movements, can probably monitor all communications and my escape cannot be prevented (or can it be? Could a 3-D trap be constructed to hold a 4-D being within the plane? Hmm).
I could go on and on here, and am likely to in my own mind as I've only really started thinking along these lines. But it interests me that there are parallels between my 'extra-dimensional' self and the various spiritual beings mentioned in the Bible. It's possible that all one needs to be a 'higher' life form is just one additional dimension. Note also that if I had an interest in protecting these 3-D creatures from more malevolent entities in my 4-D universe, there's a limit to how well I can prepare these creatures to defend themselves: certainly, if an attack must be made from within their plane, I can at least warn them of the existence of creatures like myself, and give them some idea of the weapons likely to be employed and possible measures to be taken against them. It's unlikely that the 3-D creatures could directly harm any 4-D creatures. I'd probably have to assign guards either to individuals or to areas of 3-D space-time, to oppose those who would harm the 3-D creatures. My guards would not necessarily always win these battles.
Anyway, that's just me thinking aloud.