Of Vagueness, Mind & Body This is a tough post to answer because I’m unsure what you’re asking exactly. I can offer some information though.
The all or nothing nature of firing neurons has underlying analog features - the amount of neurochemicals trigger this effect. Then there is the recycling of neurochemicals for the synaptic clefts. Needless to say the threshold required to trigger a neuron firing is certainly not dictated purely by the amount of neurochemicals present in the synaptic cleft - Brownian motion plays a part.
Other than this if we look at GABA neurons (the most common neural inhibitors), they function by effectively stopping neurons from firing when they fire. In simplistic terms the cortex acts as an inhibitor to the midbrain (VERY simplistic, but generally what happens). You can think of this as pure animalistic reactions that are inhibited due to how sensory input is translated in the cortex - some sensory inputs bypass the brain completely (this is why paralysed people put on treadmills can ‘walk’).
Another thing I’d like to point out is the possible mistake of delineating the ‘brain’ from the ‘body’. The brain is a network that extends to your toes. A ‘brain’ without a body is just pink mush.
Lastly, the term ‘mind’ is dubious at best. The very term itself is ‘vague’. Without a ‘vague’ concept of something we’d have literally nothing to investigate, and if we had nothing to investigate we wouldn’t be conscious of anything. Essentially ‘knowing’ is ‘questioning/doubting’ that for navigational purposes is framed in the concept of ‘certainty’ in some instances so we have a sense of orientation in order to explore.