The fourth ray of Harmony is one of the most interesting energies of the minor four, and one of the most important during this phase of human evolution. It is not the ray which produces the creative arts, as is most commonly believed, but in its positive expression [it] produces a dynamic system of balance which tunes and harmonizes the many frequencies in the instrument to the frequency of the Soul.
In the case of the probationer on the path, this energy manifests first as an observation of the pairs of opposites. This is true to greater or lesser degree, depending upon his particular ray makeup. If the energy is not predominant somewhere in his makeup, it is still there in lesser degree, since these minor four are the attributes of the Soul, and part if Its nature.
This is an important point, for there is a great misunderstanding in the minds of many students anent this subject of available characteristics and attributes. Many believe that if they do not have a particular ray energy predominant in their makeup that they lack in this quality – that it is not available to them. This need not be true, since the seven ray qualities constitute the nature of the Soul. One particular quality may or may not be predominant, but it is nonetheless available, and upon full Soul development all qualities, the seven-fold nature of the Soul, will be expressing perfectly in time and space.
As the aspirant becomes a probationer disciple, he begins to observe and to recognize the pairs of opposites as they are manifesting within his consciousness and its instrument.
He observes how he fluctuates from the so-called good to the so-called bad, how he swings with the pendulum from one extreme to the other, and gradually he realizes that in order to balance the opposites, he must take the middle path, swinging neither to the right nor to the left.
As this concept makes its impression upon him, it is usually misinterpreted to mean a path of non-action — of passivity. This is a glamour of the astral plane, one of the astral vapors which so distort Truth that it becomes non-recognizable in its appearance.
This harmonizing energy is anything but passive in quality. It is essentially dynamic, for it fuses the pairs of opposites together in such a way as to render them whole, thus producing a whole tone in the sounding Word of God.
For some time, then, the probationer attempts to become passive, to take the path of least resistance, and this does serve a purpose since it renders him more easily the observer.
Moving along what he considers to be the middle way, he observes the pairs of opposites, endeavoring to balance them from his central point of focus.
“Alone I stand upon the scales, and reaching out I bring into all relationships that peculiar motion which results in balance.”
That peculiar motion is the expression of the fourth ray of Harmony, which enables the probationer to move from passivity into action — to reach out and bring the opposites into the central point of focus where balance is restored, where the so-called bad is transmuted into good.
At this point the probationer begins to comprehend the Law of Paradox. He learns that all concepts, all systems of thought, must be based upon a causal truth. Anything that is must have its foundation in reality or it could not be. At the same time everything that is must be false for it is confined in a form. Thus, he applies the Law of Paradox to every concept, every form, every experience with which he is familiar, learning to understand the polar opposites, the so-called good and bad as “essence” and “form”. Nothing is strictly true or false, good or bad; everything is both, and through a recognition of this, the essence or reality and the form or substance can be so fused as to produce the whole tone, which in its magical effect tunes or harmonizes all other frequencies within its range of influence.
This is Harmony — a differentiated expression of Love-Wisdom. It produces that understanding which is a prerequisite to right relationship, whether it be with the One Life, a situation, or among peoples. 
 From an oral presentation by Lucille Cedercrans.
 The Nature of The Soul, p. 153-155