after thinking about it for a while, i think i came up with a way of understanding the relationship between the spiritual energy called on in spell craft. and the physical components we so often see used in the process. walk with me as i torture this metaphor.
Think of a glass filled with water. the water is unto the glass much like the energy is unto the spell-component. it is the water, not the glass, that will quench your thirst. and an empty cup can never do that no matter what you do with it. however, this doesn’t mean the glass is meaningless or arbitrary. for it is the glass that we use to lift the water to our lips and take a drink. without that,the process would be much more difficult, sometimes even impossible. .
while this relationship is phrased in the above as a metaphor, in many ways its also quiet literal. a spells physical components are assembled into a vessel for the energy to rest in. much like a glass, cup or vase. once pored into the vessel, the water takes on that vessels shape from the inside. spiritual energy does much the same when its flowed into a prepared vessel. the various layers of meaning and correspondence serve to help shape the intention programmed into the energy. in short, it does some of the programming for you. some materials even add a bit of an energetic boost drawn from the sympathy they have with other sources of power. for our water-and-glass metaphor, i suppose you could liken this to adding a twist of lemon to make it all the more refreshing. .
you could take this idea one step further and compare some forms of spell-prop as energy bottles. we can store water in bottles for later use when we know we’l need it. likewise we can store energy in spell components to wait for just the right time to express it.