"A thought-form can also act as a poisoning agent, and poison all the springs of life. . . .A violent dislike, a gnawing worry, a jealousy, a constant anxiety, and a longing for something or someone, may act so potently as an irritant or poison that the entire life is spoilt, and service is rendered futile. The entire life is embittered and devitalised by the embodied worry, hatred and desire. All relationships with other people are rendered equally futile or even definitely harmful, for the worried or suspicious aspirant spoils the home circle or his group of friends, by his inner poisonous attitude, governed by an idea. His relation to his own soul and the strength of the contact with the world of spiritual ideas is at a standstill, for he cannot progress onward, and is held back by the poison in his mental system. His vision becomes distorted, his nature corroded, and all his relationships impeded by the wearing, nagging thoughts which he himself embodies in form and which have a life so powerful that they can poison him." (A Treatise on White Magic, p. 489)

http://www.esoteric-philosophy.net/thoutforms.html

Thought-form Building Rules

"The necessity for clear thinking and the elimination of idle, destructive and negative thoughts, becomes increasingly apparent as the aspirant progresses on his way. As the power of the mind increases, and as the human being differentiates his thoughts increasingly from mass thought, he inevitably builds thought substance into form. It is at first automatic and unconscious. He can not help so doing, and fortunately, for the race, the forms constructed are so feeble that they are largely innocuous, or so in line with mass thought that they are negligible in their effect. But as man evolves his power, and his capacity to harm or to help increases, and unless he learns to build rightly, and correctly to motivate that which he has built, he will become a destructive agency and a centre of harmful force -- destroying and harming not only himself, as we shall see shortly, but equally hurting and harming those who vibrate to his note.
Granted all this, you might appositely inquire: Are there some simple rules which the earnest and sincere beginner could apply to this science of building, and which are so clear and concise that they will produce the needed effect? There are, and I will state them simply so that the beginner will, if he follows them, escape the dangers of black magic, and learn to build in line with the Plan. He will, if he follows the rules I give, avoid the intricate problem which he has himself blindly constructed, and which will indeed shut out the light of day, darken his world, and imprison him in a wall of forms which will embody for him his own peculiar great illusion.
These rules may sound too simple for the learned aspirant, but for those who are willing to become as little children, they will be found to be a safe guide into truth and will eventually make them able to pass the tests for adeptship. Some are couched in terms symbolic, others are necessarily blinds, still others express the truth just as it is.

1. View the world of thought, and separate the false out of the true.

2. Learn the meaning of illusion, and in its midst locate the golden thread of truth.

3.Control the body of emotion, for the waves that rise upon the stormy seas of life engulf the swimmer, shut out the sun and render all plans futile.

4. Discover that thou hast a mind and learn its dual use.

5. Concentrate the thinking principle, and be the master of thy mental world.

6. Learn that the thinker and his thought, and that which is the means of thought, are diverse in their nature, yet one in ultimate reality.

7. Act as the thinker, and learn it is not right to prostitute thy thought to the base use of separative desire.

8. The energy of thought is for the good of all and for the furtherance of the Plan of God. Use it not therefore for thy selfish ends.

9. Before a thought-form is by thee constructed, vision its purpose, ascertain its goal, and verify the motive.

10. For thee, the aspirant on the way of life, the way of conscious building is not yet the goal. The work of cleaning out the atmosphere of thought, of barring fast the doors of thought to hate and pain, to fear, and jealousy and low desire, must first preced the conscious work of building. See to thy aura, oh traveller on the way.

11. Watch close the gates of thought. Sentinel desire. Cast out all fear, all hate, all greed. Look out and up.

12. Because thy life is mostly centred on the plane of concrete life, thy words and speech will indicate thy thought. To these pay close attention.

13. Speech is of triple kind. The idle words will each produce effect. If good and kind, naught need be done. If otherwise, the paying of the price cannot long be delayed.
The selfish words, sent forth with strong intent, build up a wall of separation. Long time it takes to break that wall and so release the stored-up, selfish purpose. See to thy motive, and seek to use those words which blend thy little life with the large purpose of the will of God.
The word of hate, the cruel speech which ruins those who feel the spell, the poisonous gossip, passed along because it gives a thrill -- these words kill the flickering impulses of the soul, cut at the roots of life, and so bring death.
If spoken in the light of day, just retribution will they bring; when spoken and then registered as lies, they strengthen that illusory world in which the speaker lives, and holds him back from liberation.
If uttered with intent to hurt, to bruise and kill, they wander back to him who sent them forth, and him they bruise and kill.

14. The idle thought, the selfish thought, the cruel hateful thought, if rendered into word, produce a prison, poison all the springs of life, lead to disease, and cause disaster and delay. Therefore, be sweet and kind and good as far as in thee lies. Keep silence and the light will enter in.

15. Speak not of self. Pity not thy fate. The thought of self and of thy lower destiny, prevent the inner voice of thine own soul from striking upon thine ear. Speak of the soul; enlarge upon the plan; forget thyself in building for the world. Thus is the law of form offset. Thus can the rule of love enter upon that world." (A Treatise on White Magic, p. 472/5)

Thought Power

"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 vitalisation. . . . 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 generalisation 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 visualise, 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 focussing 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 visualisations; 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)

Visualisation

"The secret of all true meditation work in its earliar stages, is the power to visualise . . . Meditation techniques must and will embody visualisation as a primary step, for the following reasons:

1. Visualisation is the initial step in the demonstration of the occult law that "energy follows thought" . . .

2. The power to visualise is the form-building aspect of the creative imagination . . . This process of energy direction can become a spiritual habit if disciples would begin to do it slowly and gradually. At first, the visualising process may seem to you to be laboured and profitless but, if you persevere, you will find eventually that it becomes effortless and effective . . .

3. The power to visualise correctly is one definite mode of ascertaining truth or falsity . . .
This visualising process, and this use of the imagination, form the first two steps in the activity of thought-form building. It is with these self-created forms -- embodying spiritual ideas and divine purpose -- that the Masters work and hierarchical purpose takes shape. Therefore, my disciples, it is essential that you begin with deliberation and slowly to work in this manner, and to use the above information constructively and creatively." (Discipleship in the New Age, Vol. I, p. 89/91)

"The clue of all this esoteric work demanded by Shamballa, is to be found in the development of the Art of Visualisation. Through visualisation, three expressions of the human consciousness will become possible:

1. The antahkarana can be built, and the shining of the Triad be definitely seen. Such will be the new vision -- an outcome of the development of the sense of vision.

2. Groups, large wholes and major syntheses, will also be visualised, and this will lead to a definite expansion of consciousness. Thus the sense of sythesis will be unfolded.

3. All creative art will be fostered by this training, and the new art of the future in all departments of creativity, will be rapidly developed as the training proceeds. The unfoldment of the sense of vision and the sense of sythesis, through visualisation, will lead to a sense of livingness in form." (The Rays and the Initiations, p. 123)