The “whole” is neither the sum of parts, nor a unity. From the perspective of relative knowledge it would more correctly be stated to be multiplicity found in unity, but as soon as you start conceiving a thing called “unity” you are lost. This is philosophical.
From the perspective of absolute truth, there is nothing that can be accurately said—language is incapable of encompassing the absolute. Poetry helps a little though.
From the perspective of how we perceive, clearly our senses deliver a continuous (for the most part) stream of nerve impulses to the brain. Science asserts that then, once those impulses reach the brain, it and its constituent, “consciousness,” creates the experience of colorful light, sounds, sensations of touch and stretch, smells, and tastes, and somehow the brain organizes that into intelligible experiences—clearly an interpretation of what is arriving at any time. At the present time, however, this process is just asserted, and not shown, by scientists, who are constrained by their adherence to a certain understanding of reality, at any given time.
A better way to understand what is happening—a more Buddhist way—is to see all of those nerve impulses reaching various areas of the brain as the conditions for the manifestation in mind (mind and brain not being equivalent) of the various perceptions that flood over us throughout our waking moments. In this way, karma, and character, and even mood, as well as the body of our current state of understanding (our ‘knowledge’) have a place in the conditioning of what arises in mind. This way of understanding what is happening better fits both our wakeful experiences and our dreams while sleeping, or being ‘unconscious’.
In the end, mind is the only source of manifested experiences. So what do we perceive—the whole? The “whole” of what exactly? Our imaginary entities and their ‘wholes’ and ‘parts’?
Thus, direct meditative knowledge of the wisdom mind is the goal of mind-training, just as having a “ripped body” is the goal of weight-training. Wholes and parts are just concepts, as are what they describe, and these are like the wind: they arrive and create chaos in our mind, blowing concepts around like leaves, and then suddenly, they disappear once one has trained their mind to chill out and pay attention to what is truly happening.