As motion causes motion, so the silent life becomes active in a certain part, and creates every moment more and more activity, losing thereby the peace of the original silent life. It is the grade of activity of these vibrations that accounts for the various planes of existence. These planes are imagined to differ from one another, but in reality they cannot be entirely detached and made separate from one another. The activity of vibrations makes them grosser, and thus the earth is born of the heavens.