This article gathers scattered indications in Bailey's books about how the soul and personality rays relate to the astrological chart.
The personality ray changes
As a sub-ray, the personality ray changes from life to life until all seven sub-rays of the monadic ray have been experienced. An evolved soul reviews its own note before a new life and itself chooses the vibration of the next personality. Each ray works primarily through one centre and through the other six in a certain order; this is what causes the personality ray to shift from life to life.
Rulers and rays
The personality ray expresses itself through the orthodox ruler, the soul ray through the esoteric ruler. The Sun sign, with its orthodox rulers, governs the personality and gives a summary of past lives. In undeveloped people the non-sacred planets dominate; at the level of the disciple the throat centre is ruled by Saturn, the head centre by Uranus and the centre between the eyebrows by Mercury. After the third initiation these rulers change again.
Rays first
Until the astrologer is sure of the subject's two major rays, dogmatic statements are impossible.Esoteric Astrology (EA), p. 513, paraphrased
The Tibetan says the astrologer must determine the soul ray before casting an adequate horoscope of the soul. The soul ray forms a triangle of three centres and their sacred planets. Over time the signs are rearranged according to the soul ray and the influence of the present rulers wanes.
The third and fifth rays
The third and fifth rays hold a special place in the great cycles of both the individual and humanity. The third ray governs the whole development of the race; the fifth, through concrete knowledge and science, is the secondary influence carrying present humanity forward. It is also said that the personality of everyone who seeks to expand consciousness passes through the third ray, in connection with the solar plexus centre.
Aquarius and the seventh ray
When the seventh ray is active and the Sun is in Aquarius, the combined light of the seven energies becomes visible on the physical plane. This combination appears at times of planetary crisis and is being established now with the start of the Aquarian Age. In a personal chart a similar combination, such as a sixth ray soul living with a seventh ray personality, signals a strong opportunity for transformation.