1. Didactic utility. In my 2020 article I mentioned the didactic utility of organizing the metals and nonmetals in terms of the use of tradition; analogy; descriptive chemistry; systematics; symmetry; contrast; and aspects of learning theory. By first explaining the conventional dichotomy of metals and nonmetals, or as a trichotomy that adds metalloids as an intermediary class, the stage set for a more refined classification. Parsing the elements into four complementary sets allows for a prelude to group-by-group chemistry that better recognizes the continuity and gradations inherent in nature. This reflects a philosophical stance that recognizes a spectrum of properties in the natural world. ) commented that one of the objectives of taxonomy (in biology) was: