The sixth ray is the one Bailey's system says is going out. Its quality is devotion: single hearted aspiration, loyalty to a person or a cause, the readiness to give everything to one thing. The literature associates it with the religious temperament in its most concentrated form, and with the two thousand years the scheme calls the Piscean age, which it holds to be ending.
That gives the sixth ray a peculiar tone in the writing. It is treated with respect and with something close to regret, as a great instrument now being withdrawn. Devotion built the monasteries, the missions and the martyrdoms, and the same quality, the system says, built the fanaticisms: the shadow named for the sixth ray is exactly the virtue held too tightly, an idealism that has stopped checking itself against anything outside the ideal.
The historical reading here is testable in a way the rest of the scheme is not, and it does not fare especially well. Predictions about a declining religious age were commonplace in the Theosophical milieu of the 1930s, they belong to a wider secularisation thesis that has been substantially revised since, and the atlas holds religious demography that does not show the picture Bailey expected. What survives is not the forecast but the description. The sixth ray names a real and recognisable way of being committed, and it names the failure mode of that commitment without flinching, which is more than most typologies do for their favourites.