The author asserts that the procedure of classification needs, so to speak, a calculation. He discusses as follows.
In order to prevent the confusion of classification, logic has taught that the principle of divison must be not multiple, but single. In other words, the viewpoint of classification must be single and unified. But practically multiple viewpoints are necessary very often. Without them we cannot characterize any book or other kind of material on the table of classification. Here the author proposes the following principle: If we want to make a classification which contains many viewpoints (principles of division), we must classify terms step by step, and thus take so many steps of classification that every one of them includes single principle of division. The method of decimal classification is applied only to the last step. The other steps do not appear on the table of decimal classification.
But the process of the other classifying steps before the last result is indispensable to get better classification, and we call it the calculation of classification. If we practice the calculation, we get a classification where terms locate regularly according to the grade of similarity or difference. It is desirable that the process of calculation is recorded, preserved, and, if possible, published.
