Each chain consists of seven globes, and both globes and chains observe the rule of descending into matter and then rising out of it again.  In order to make this comprehensible let us take as an example the chain to which our Earth belongs.  At the present time it is in its fourth or most material incarnation, and therefore three of its globes belong to the physical world, two to the astral world, and two to the lower part of the mental world.  The wave of divine Life passes in succession from globe to globe of this chain, beginning with one of the highest, descending gradually to the lowest and then climbing again to the same level as that at which it began.

Let us for convenience of reference label the seven globes by the earlier letters of the alphabet, and number the incarnations in order.  Thus, as this is the fourth incarnation of our chain, the first globe in this incarnation will be 4A, the second 4B, the third 4C, the fourth (which is our Earth) 4D, and so on.

These globes are not all composed of physical matter. 4A contains no matter lower than that of the mental world; it has its counterpart in all the worlds higher than that, but nothing below it. 4B exists in the astral world; but 4C is a physical globe, visible to our telescopes, and is in fact the planet which we know as Mars.  Globe 4D is our own Earth, on which the life-wave of the chain is at present in action.  Globe 4E is the planet which we call Mercury—­also in the physical world.  Globe 4F is in the astral world, corresponding on the ascending arc to globe 4B in the descent; while globe 4G corresponds to globe 4A in having its lowest manifestation in the lower part of the mental world.  Thus it will be seen that we have a scheme of globes starting in the lower mental world, dipping through the astral into the physical and then rising into the lower mental through the astral again.

Just as the succession of the globes in a chain constitutes a descent into matter and an ascent from it again, so do the successive incarnations of a chain.  We have described the condition of affairs in the fourth incarnation; looking back at the third, we find that that commences not on the lower level of the mental world but on the higher.  Globes 3A and 3G, then, are both of higher mental matter, while globes 3B and 3F are at the lower mental level.  Globes 3C and 3E belong to the astral world, and only globe 3D is visible in the physical world.  Although this third incarnation of our chain is long past, the corpse of this physical globe 3D is still visible to us in the shape of that dead planet the Moon, whence that third incarnation is usually called the lunar chain.

The fifth incarnation of our chain, which still lies very far in the future, will correspond to the third.  In that, globes 5A and 5G will be built of higher mental matter, globes 5B and 5F of lower mental, globes 5C and 5E of astral matter, and only globe 5D will be in the physical world.  This planet 5D is of course not yet in existence.