These types are clearly distinguishable in all the kingdoms, and the successive forms taken by any one of them form a connected series, so that animals, vegetables, minerals and the varieties of the elemental creatures may all be arranged into seven great groups, and the life coming along one of those lines will not diverge into any of the others.
No detailed list has yet been made of the animals, plants or minerals from this point of view; but it is certain that the life which is found ensouling a mineral of a particular type will never vivify a mineral of any other type than its own, though within that type it may vary.

When it passes on to the vegetable and animal kingdoms it will inhabit vegetables and animals of that type and of no other; and when it eventually reaches humanity it will individualize into men of that type and of no other.
The method of individualization is the raising of the soul of a particular animal to a level so much higher than that attained by its group-soul that it can no longer return to the latter.

This cannot be done with _any_ animal, but only with those whose brain is developed to a certain level, and the method usually adopted to acquire such mental development is to bring the animal into close contact with man.

Individualization, therefore, is possible only for domestic animals, and only for certain kinds even of those.

At the head of each of the seven types stands one kind of domestic animal--the dog for one, the cat for another, the elephant for a third, the monkey for a fourth, and so on.