Ah. Pure energy. Matter without form...Materialism has traditionally been good at exploring what things are made of. But it has a less good track record explaining why things have a certain shape or configuration. This is where a renewed attention to Aristotle at least helps to clarify things.
Materialism's comfort zone is reducing things to smaller things. So it's not surprising that it skews towards emphasizing what things are made of at the expense of the form they assume.
Incidentally, this is the major distinction between what Marx calls “metaphysical” materialism and his dialectical materialism. For Marx, materialism has to do with form: the configurations of economic relations, relations of class, between superstructure and base and so on. (The very terms “superstructure” and “base” connote a formal way of thinking.)
For Aristotle, there are four kinds of cause: material, formal, efficient and final. What is something made of? (Material.) What shape does it have? (Formal.) What does it do, how does it work? (Efficient.) And what's it for? (Final.)
From these, we get the rhetorical trope of metonymy, which applies to the four causes.
“Okay frog. Burn rubber.” (Material cause of tires.) (HT The Muppet Movie)
“I like your wheels.” A car has wheels as part of its form.
“Can I bum a smoke?” You smoke a cigarette (efficient cause).
“I don't smoke cancer sticks.” The final cause of a cigarette.
Metonymy is interesting because it's literalistic. Unlike metaphor, it uses parts of an object that really are genuine parts of that object. I shall have to think on this more when it comes to thinking about causality for my book project.
Materialism defaults to reductionism if it only considers material causes. Thus biology is good at reducing lifeforms to molecules, but not so good yet at thinking morphogenesis. Some big questions about form remain unanswered.
The therapeutic value of Aristotle is that he lets us see form as a cause, not as some kind of add-on, a bottle into which a liquid (the “real” thing) is poured. Form is just as real as content, and just as fundamental.
Sorry Mr. Spock—there is no matter devoid of form...