“Only when Spirit, by the power of thought, controls the material vehicles, does the subjective life assume its rightful place, does the God within shine and blaze forth till the form is lost from sight, and “The path of the just shine ever more and more until the day be with us.” (A Treatise on Cosmic Fire, p. 140)

“These . . .objectives necessitate a clear comprehension among such vital thinkers and workers, of the power of thought; of the direction of thought currents, of the science of thought building, of the manipulation under law and order of mental matter, and of the process of thought manifestation through the two factors of sound and vitalization. . . . No worker for humanity becomes of real assistance until he (consciously and with full knowledge of his work) definitely directs his thought energy towards some particular channel of service to the race.” (A Treatise on Cosmic Fire, p. 955)

“The second question asks, whether an individual or a group can heal by thought power.
Most certainly the generalization can be made, that an individual and a group can heal, and that thought can play its potent part in the healing process, but not thought alone and unaided. Thought can be the directing agency of forces and energies, which can disrupt and dispel disease, but the process must be aided by the power to visualize, by an ability to work with particular forces as is deemed advisable, by an understanding of the rays and their types of energies, and also by a capacity to handle light substance, as it is called. To these powers must be added the ability to be en rapport with the one to be healed, plus a loving heart. In fact, once these conditions are met, too much use of the thinking faculty, and too potent a use of the mind processes, can arrest and hinder the healing work. Thought has to condition the initial incentive, bringing the intelligence of the man to bear upon the problem of healing, and a comprehension of the nature of the one to be healed; but once it has aided in focusing the attention of the healer and the healing group, it should become a steady but subconscious directive agent, and nothing more than that.
The healing is accomplished, when possible, by the use of energy rightly directed, and by detailed visualizations; love also plays a great part, as does the mind in the early stage. Perhaps I should say that a loving heart is one of the most potent of all energies employed. . . .
Thought neither cures disease nor causes it. Thought must be employed in the processes, but it is not the sole or the most important agent. The mind can direct energy, and this energy can, in its turn, produce over-stimulation of the brain and of the body cells, and so cause nervous trouble and sometimes brain disease, but the mind itself and thinking, per se, cannot cause disease and trouble in the physical body.” (Esoteric Healing, p. 96/7)

~  Ascended Master Djwhal Khul through Alice Bailey

A Treatise on Cosmic Fire by Alice Bailey

A Treatise on White Magic by Alice Bailey

Esoteric Healing (A Treatise on the Seven Rays) by Alice Bailey