Summum genus

While the matter-form composite establishes the physicist's summum genus, the esse-essentia composite establishes the metaphysician's; while living and non-living bodies divide the physicist's summum genus, spiritual and corporeal beings divide the metaphysician's.(22) The philosopher qua physicist knows little or nothing of spiritual substance; to the philosopher qua metaphysician, however, spiritual substances are simple forms exercising esse per se.(23) In chapters 4 and 5 Thomas undertakes his metaphysical analysis of the human soul.