Mental concentration is a difficult exercise which requires preparation. This preparation consists first in calming ourselves, because an agitated state disperses psychic energies. If we attempt to concentrate without having first established inner calm, we shock the cells of our brain and prevent them from doing their work properly. Every object has a natural inertia, and we cannot stimulate a desired movement all at once. We must start with a very gentle push, and only after a certain time will it assume on its own the momentum we wish. Never forget that the cells of our organism are living creatures, which we must neither force nor shock.