On the Fundamental and the Applied in Science and Education

Fonvizin's Mitrofanushka discussed the word "door" in roughly the following way: the word is an adjective as long as and insofar as the object it designates is applied in some task and works well. But when the mentioned door is present to his mind's eye only in its essential potentiality, only in itself, and has not been applied yet in some task, then Mitrofanushka defines such a door as a substantive noun. He makes it clear: "this door is for the time being a substantive."