Sentence:  Perhaps the last named, mass-energy, comes closest to converying the Aristotelian idea of <WSD>protomatter</WSD> as the basic stuff of the universe. Whatever quarks may be, or leptons and hadrons in their various forms, it seems generally agreed that all are manifestations of mass-energy, the ultimate matrix to which science seems to have come in identifying the material cause of the universe. 
Meaning of the word marked with <WSD> tags:  The ultimate basis of physical substance, before it has been given form.