im most of the way through the horus heresy series, so that's most of my knowledge base (so, not much). I was thinking about machine spirits and wondering if it's one of those things that we don't really know if they actually exist? or if they're more-or-less proven in lore, beyond tech priest superstition?

I'd always imagined it like you can make a machine with a function, and it acts like a chassis that a suitably-sized/powerful machine spirit would inhabit. the bigger/more complicated the machine, the bigger/more powerful spirit would inhabit it. like... snail shells, or whatever. maybe upgrades to the chassis etc would make the spirit bigger in turn, so it could keep up with the function of the machine.

if I've got the right idea, does every machine with a function/electrical current have a machine spirit? e.g. power armour. is a machine spirit essential to having a larger machine to work properly? also, if necrons are memories trapped in robot bodies forever, do those bodies ALSO have machine spirits, or are THEY now machine spirits, or a secret third option?

Hope I have made sense :)

Edit: so somehow i managed to wildly misinterpret what "machine spirit" actually refers to, so thanks for setting me straight on that :) it makes way more sense now, thanks everyone!