To establish the structure, we were previously guided not by the full sum of combinations that a given crystal exhibits, but only by a small number of the most important pairs of faces. In this regard, as we see, no change has occurred. Even now we must first of all note these most important forms, but earlier we calculated the density of these forms, since, after all, the basis was the sequence of faces in order of importance. Now this calculation disappears and is even significantly simplified, because it only remains to determine from these forms which of the three zones these forms fall into.
