3.4. Generalities Concerning the Classification System

In the actual process of classification there are two precepts of crucial importance:

1. The classification system shall be so defined that different observers will obtain similar results systematically; that is, conflicting criteria should not be allowed to interfere with the precision with which the system is defined.

2. A specimen that does not resemble any of the standard categories should not be forced into membership of one of them.

In the most basic manner, a classification system is defined by the properties of the specimens which have been classified; and each group is defined by the specimens which have been assigned to it. When the number of classified specimens has become sufficiently large, the physical properties of the components of each group can be investigated with precision, and the system can then be placed on a quantitative basis.