The Synthesis perspective concurs with the view that physical bodies are extremely complex organic instruments. Materialists make a similar claim, but it is inconsistent within their framework. They seem to neglect the facts that instruments are always built with a purpose and their working has to be externally initiated (at least the working of the first one that may create and initiate the working of other machines). This inconsistency is avoided here since the Intent and purpose are acknowledged. ‘Instrument' does not imply though, that the body is simply a mechanical thing. Its enormous complexity and organisation is unparalleled, so a real comparison with machines is admittedly a gross simplification. In any case, the body is considered the material aspect of a living system that consists of comparatively slow but very dense energy. This is why physical sensations (e.g. pain, hunger) can have such a strong effect. The body is the intermediary through which the interaction between the non-material and material, the soul and the environment, occurs. The body enables physical life, but itself is not alive. It is a part of a living system for as long as it is coupled with the soul. To say that the body dies feels counter-intuitive because it has never lived.
The relation between the body and the soul
Asking where the soul is in relation to the body (e.g. whether it is in the body) does not make sense, since they do not share the same ‘space'. It could be said, though, that the soul encompasses the body it is connected to, because it belongs to the realty within which the physical domain is situated, and because it has potentially a wider scope than the body (as the one who dreams includes the one in the dream). On the other hand, the body is largely a boundary at least for the part of the soul during the life-time. So, depending on the perspective, the soul ‘encloses' the body and the body ‘encloses' the soul. An urge to see the soul as being somewhere else in space (usually above as if it was a satellite) should also be resisted. This is as misleading as imaging that the soul dwells in the body. One metaphor, however crude, may, perhaps, help to avoid these temptations: the soul and the body can be compared to a wind and a sail. A sail captures some wind, and the wind blows into the sail, so they interact for a while. But, where does the wind dwell? Not in a particular place, it is a moving mass of air, in which the sail, boat and everything else is submerged.
The purpose of the body
The function of the body is to hold the soul grounded (to slow down the energy), which enables its rudimentary shaping. The body allows dynamism, but a limited one. So besides enabling communication with the environment, it also creates the boundaries that are needed until the non-material aspect is capable of self-control. In other words, the body has a role to stabilise and protect (primarily from the volatile exercise of agency and an excessive amount of input). As already mentioned, the senses are the first instance of selecting that of which we are going to be aware. This narrowing of the soul is necessary to allow a gradual development. Without these restrictions, it would be like a radio or TV receiver that picks up all the available transmitting signals; they would not produce potential information, but a meaningless noise.
The contribution to development
An interesting fact is that the brain is allowed to use an extraordinary amount of energy relative to its size. In humans, as much as 30% of the body's resting energy expenditure (oxygen and glucose) is due to the brain, while its mass accounts for around 3% of one's weight - ten times more than its share. No other part of the body by far is in such a privileged position, which strongly indicates that biological evolution is geared towards the development of the brain. It seems that the body exists to support the brain, not the other way around. This is congruent with common sense: if you had to choose, would you rather be without the body and retain the brain, or without the brain and retain the body?
Why does the soul not separate from the body during a lifetime (or join another body)?
For the same reason why people do not jump out of cars at full speed. A car must stop or substantially slow down so that the person who is in it can get out safely. Similarly, the body and the brain must stop or at least substantially slow down and the corresponding soul must dis-identify in order to separate. Connecting to another body is practically impossible, not only because every body has its own unique code, but also because it would have to be ‘vacant', not already resonating with another soul. In such a case it would not be a functional body any way (although purely physico-chemical processes in some parts of the body can continue even without the connection).