. As advancement continues it is gradually stirred into
alertness by vibrations which reach it from the lower bodies. This comes
but slowly, because the activities of man in the earlier stages of his
evolution are not of a character to obtain expression in matter so fine as
that of the higher mental body; but when a man reaches the stage where he
is capable either of abstract thought or of unselfish emotion the matter of
the causal body is aroused into response.

When these rates of undulation are awakened within him they show themselves
in his causal body as colours, so that instead of being a mere transparent
bubble it gradually becomes a sphere filled with matter of the most lovely
and delicate hues--an object beautiful beyond all conception. It is found
by experience that these colours are significant. The vibration which
denotes the power of unselfish affection shows itself as a pale
rose-colour; that which indicates high intellectual power is yellow; that
which expresses sympathy is green, while blue betokens devotional feeling,
and a luminous lilac-blue typifies the higher spirituality. The same scheme
of colour-significance applies to the bodies which are built of denser
matter, but as we approach the physical world the hues are in every case by
comparison grosser--not only less delicate but also less living.

In the course of evolution in the lower worlds man often introduces into
his vehicles qualities which are undesirable and entirely inappropriate for
his life as an ego--such, for example, as pride, irritability, sensuality.
These, like the rest, are reducible to vibrations, but they are in all
cases vibrations of the lower subdivisions of their respective worlds, and
therefore they cannot reproduce themselves in the causal body, which is
built exclusively of the matter of the three higher subdivisions of its
world. For each section of the astral body acts strongly upon the
corresponding section of the mental body, but only upon the corresponding
section; it cannot influence any other part. So the causal body can be
affected only by the three higher portions of the astral body; and the
oscillations of those represent only good qualities.

The practical effect of this is that the man can build into the ego (that
is, into his true self) nothing but good qualities; the evil qualities
which he develops are in their nature transitory and must be thrown aside
as he advances, because he has no longer within him ma