The knowledge that has been gained about the nature of matter in recent years is helpful in understanding the activities of consciousness. The atom is found to be a center of force, and we are at the point where matter, as we have known it, disappears. All the force and consciousness of the solar system is, of course, but the life of the Logos, and on higher planes the distinctions we observe here fade out. Matter becomes a very different thing from the matter we know. The ether of the physical world is almost inconceivably tenuous matter. Yet it is gross when compared to the lowest grade of astral matter. The matter of the mental world is enormously rarer than the most tenuous matter of the astral world. In view of these facts it requires no stress of the imagination to understand that the matter of the higher planes is responsive to the vibrations of consciousness.
The outraying energies of the individualized center of consciousness act upon the matter of the plane and draw about it a film that slowly grows into a vehicle through which consciousness can be more fully expressed, and which serves as a point of vantage from which its expression can be extended to lower planes.
The seven subdivisions of the mental world fall naturally into two groups, composed of the three higher and the four lower grades of matter. The ego, anchored in the matter of the two planes above the mental world, descends to the upper levels of the mental and the vesture of matter with which it clothes itself is known as the causal body. Sending its energies downward, or outward, to the lower levels of the mental world, it establishes itself there in what slowly becomes a mental body. Again in the astral world the process is repeated and a vehicle of consciousness is formed of astral matter. The physical body is the lowest and last of the vehicles to be formed and as it is slowly built, in the months preceding birth, the matter it contains falls into place under the operation of occult laws which permit no element of chance to enter into its construction.
Each of these bodies serves as a vehicle of consciousness on the plane to which it belongs. The soul is evolving simultaneously in each of the worlds, physical, astral and mental, and these various bodies enable it to receive the vibrations of the plane they belong to and thus to be conscious there. The mental body is the seat of intellectual activity. Thought arises as a vibration in it and passes through the astral body into the physical brain. Whenever we think we are using the mental body. The astral body is the seat of emotion. With it we feel. All emotion passes from it to the physical body to be expressed in the material world. The astral world is also called the emotional world, as the mental plane is called the mental world. The physical body is the soul's instrument of action. It attaches it to the physical world, enables the consciousness to contact material objects and to move and express on the material plane the thoughts and emotions generated in the mental and astral bodies.