Some authors have conceptualized depression as a "depletion syndrome" because of the prominence of fatigability; they postulate that the patient exhausts his available energy during the period prior to the onset of the depression and that the depressed state represents a kind of hibernation, during which the patient gradually builds up a new story of energy.
Concerning matter, we have been all wrong. What we have called matter is energy, whose vibration has been so lowered as to be perceptible to the senses. There is no matter.
So we find that the three possible solutions of the great problem of increasing human energy are answered by the three words: food, peace, work... Their scientific meaning and purpose now clear to me: food to increase the mass, peace to diminish the retarding force, and work to increase the force accelerating human movement.