Some of the most explicit information that Edgar Cayce provided on the topic of glands as spiritual centers comes from a series of readings given on the last book of the Christian Bible, the Revelation.  Cayce's interpretation of the Revelation focuses on the symbols in John's vision as indicative of the soul's journey, as a psychospiritual odessey.  Cayce stated that virtually all of the symbols relate to physiological processes within the body.  When the symbols appear in sevens (as in churches, candlesticks, angels, stars, etc), they usually refer to the seven primary endocrine glands

Here are some excerpts from reading 281-30 that discuss this point.  I am also including an illustration of the body with the seven primary endocrine colored in the rainbow spectrum that Cayce said would be representative of the energy patterns for these centers.



(Q)  Please discuss more fully the relation of colors to the seven major glandular centers.  Do the colors vary for each center with different individuals, or may definite colors be associated with each center?
(A)  Both.  For to each - remember, to study each of these in the light not only of what has just been given but that as is a practical experience in the material world; as is known, vibration is the essence or the basis of color.  As color and vibration then become to the consciousness along the various centers in an individual's experience in meditation made aware, they come to mean definite experiences.  Just as anger is red, or as something depressing is blue; yet in their shades, their tones, their activities, to each they begin with the use of same in the experience to mean those various stages.  For instance, while red is anger, rosy to most souls means delight and joy - yet to others, as they are formed in their transmission from center to center, come to mean or to express what MANNER
of joy; whether that as would arise from a material, a mental or a spiritual experience.  Just as may be seen in the common interpretation of white, but with all manner of rays from same begins or comes to mean that above the aura of all in its vibration from the body and from the activity of the
mental experience when the various centers are vibrating to color.
(Q)  If so, give color for:  (1) Gonads (2) Lyden [Leydig] (3) Solar Plexus (4) Thymus (5) Thyroid (6) Pineal (7) Pituitary.
(A)  These come from the leaden, going on through to the highest - to that as is the halo.  To each they become the various forces as active throughout, and will go in the regular order of the prism.  (281-30)