n.

The physical body is in a constant state of flux, its minute particles
being continually renewed, so that it is ever building; and as it is
composed of the food we eat, the liquids we drink, the air we breathe,
and particles drawn from our physical surroundings, both people and
things, we can steadily purify it, by choosing its materials well, and
thus make it an ever purer vehicle through which to act, receptive of
subtler vibrations, responsive to purer desires, to nobler and more
elevated thoughts. For this reason all who aspired to attain to the
Mysteries were subjected to rules of diet, ablution, &c., and were
desired to be very careful as to the people with whom they associated,
and the places to which they went.

The desire body also changes, in similar fashion, but the materials for
it are expelled and drawn in by the play of the desires, arising from
the feelings, passions, and emotions. If these are coarse, the materials
built into the desire body are also coarse, while as these are purified,
the desire body grows subtle and becomes very sensitive to the higher
influences. In proportion as a man dominates his lower nature, and
becomes unselfish in his wishes, feelings, and emotions, as he makes his
love for those around him less selfish and grasping, he is purifying
this higher vehicle of consciousness; the result is that when out of the
body in sleep he has higher, purer, and more instructive experiences,
and when he leaves the physical body at death, he passes swiftly through
the intermediate state, the desire body disintegrating with great
rapidity, and not delaying him in his onward journey.

The mental body is similarly being built now, in this case by thoughts.
It will be the vehicle of consciousness in the heavenly world, but is
being built now by aspirations, by imagination, reason, judgment,
artistic faculties, by the use of all the mental powers. Such as the man
makes it, so must he wear it, and the length and richness of his
heavenly state depend on the kind of mental body he has built during his
life on earth.

As a man enters the higher evolution, this body comes into independent
activity on this side of death, and he gradually becomes conscious of
his heavenly life, even amid the whirl of mundane existence. Then he
becomes "the Son of man which is in heaven,"[249] who can speak with the
authority of knowledge on heavenly things. When the man begins to live
the life of the Son, having pass