The degree to which mind can control circumstances and dominate matter is far greater than is generally believed. Our impressions about matter are very illusory. No form of matter is permanent. Change goes on everywhere at every instant, by physical laws in the physical body and by astral and mental laws in our invisible bodies. We are not the same being, physically, mentally or spiritually, any two days in succession. The very soul itself is subject to this law of change. It may expand and shine out through the physical organism resplendent, or it may only faintly glimmer through a constantly coarsening body. What is the law of soul growth? Through adherence to what principle may we reach spiritual illumination? There are certain well established facts about the laws of growth that we should not overlook when seeking the way forward. Nothing whatever can grow without use, without activity. Inaction causes atrophy. Physiologists tell us that if the arm be tied to the body so that it cannot be used it will in time become so enfeebled, that it is of no further service. It will wither away. That is nature's law of economy. She never gives life where it is useless, where it can not, or will not, be utilized. On the other hand, exercise increases power. To increase the size and strength of muscles we must use them. This is just as true of mental and moral faculties as it is of the physical body. The only way to make the brain keen and powerful is to exercise it by original thinking. One way to gain soul powers is to give free play to the loftiest aspirations of which we are capable, and to do it systematically instead of at random. We grow to be like the things we think about. Now, the reverse of all this must be equally true. To give no thought to higher things, to become completely absorbed in material affairs, is to stifle the soul, to invite spiritual atrophy.