US-P18.086ab ।US-P18.086cd ॥
In plain words
Black iron glowing red — that is what we mean by an illustration. But an illustration and the thing it illustrates are never alike in every respect, not once, not anywhere.
Close to the Sanskrit
"Black iron [is] red-appearing" — this is called the seen instance, the illustration. But equality between the illustration and the thing illustrated is not, in every respect, ever the case.