A Classification thus made, may be tested by the same rules as those given for testing a Division; but if it does not stand the test, we must not infer that the classification is a bad one.  If the best possible, it is good, though formally imperfect:  whatever faults are found must then be charged upon the ‘matter,’ which is traditionally perverse and intractable.  If, for example, there is a hammock in the room, it must be classed not with the curtains as a warmth-fabric, but with the sofas as a support; and books and pictures may be classed as, in a peculiar sense, means of culture, though all the objects in the room may have been modified and assorted with a view to gratifying and developing good taste.

Sec. 7.  The difficulty of classifying natural objects is very great.  It is not enough to consider their external appearance:  exhaustive knowledge of their internal structure is necessary, and of the functions of every part of their structure.  This is a matter of immense research, and has occupied many of the greatest minds for very many years.  The following is a tabular outline of the classification of the

Animal Kingdom
|
-------------------
|                 |
SUB-KINGDOM,  Vertebrates    Invertebrates (10 Sub-kingdom 5)
or             |
Phylum:           |-------------------------------
|           |                  |
|      Sauropsida        Ichthyopsida
|           |                  |
|       ---------         -----------
|       |       |         |         |
CLASS:          Mammalia  Birds  Reptiles  Amphibia  Fishes
|
-------------------------
|                       |
SUB-CLASS:   Placental              Implacental
|                       |
|              -------------------
|              |                 |
DIVISION:   Monodelphia     Didelphia       Ornithodelphia
|
---------------------------------------
|          |       |         |        |
ORDER:   Quadrumana Rodentia Carnivora Ungulata Caetacea, etc.
|
----------------------------------
|                |               |
SECTION:   Pinnigrada      Plantigrada     Digitigrada
|                |               |
(Seals, etc.)  (Bears, etc.)           |
|
--------------------------------------
|          |         |        |      |
GENUS:    Mustelidae  Viverridae  Hyaaenidae  Canidae  Felidae
|            |                       |
(Weasels, etc.)   (Civets, etc.)              |
|
---------------------------------------
|      |        |       |      |      |
SPECIES:     Lion   Tiger   Leopard   Puma   Lynx   Cat, etc.
|
---------------------
|         |         |
VARIETY:   African    Syrian    Cave-lion (extinct)

As there is not space enough to tabulate such a classification in full, I have developed at each step the most interesting groups:  Vertebrates, Mammalia, Monodelphia Carnivora, Digitigrada, Felidae, Lion.  Most of the other groups in each grade are also subdivisible, though some of them contain far fewer sub-classes than others.