As Chia says, once enough of it has been stored in the head for a few weeks, it will change (to a purer form, Shen) and overflow back down the front of the body, to the navel, and still further to the base of the spine, completing the route. Now I can honestly say that this is one of the most delicious feelings one can experience! Once you feel it I doubt you'll worry about having done anything unhealthy!
On the question of the prosaic versus the mystical, I do know some people dislike Chia's straightforward approach but I personally think it's fantastic that someone who really knows his stuff this way would bother to present it in such a manner that any ignorant Westerner can use it!
What you are getting here is Taoist sexual practice as a living system, rather than history or coded poetry. You cannot really understand the Tao without doing the actual practices, or so I would think. The mystical and poetic side of Taoism will appear to you physically and personally after some time of doing the actual meditations, rather than in an etoliated form inside a book.
Also, I think Chia is anxious to make it clear that taoism is a energy system and not a religion. You could 'be a christian' and still practice the tao - in fact, Chia does precisely that. So he's attempting to make his system as universally relevant as possible, which I personally think is admirable.
Anyone who's curious should not be put off by negative reviews! This stuff really does work. Enjoy!
Chia's teachings of meditation seem accurate enough but make one fatal flaw. The whole book - all of the various levels of the energy transference exercises - lead to or stem from the Microcosmic Orbit. Through out the book, Chia states that energy moves from the sexual region, up through the body and is stored in the head.
Why would he say that and then state in one of his other books, Awaken Healing Energy of the Tao, that proper storage of this energy, after moving through the head, should be in the navel. Anyone familiar with t'ai chi knows that the navel is the center point to all of your body's energy. To store such energies in the head can lead to insanity. Very irresponsible on his part.
At the end of the book, I suppose in an effort to cover all bases, everything from the pubococcygeal muscle to refexology gets a paragraph or two. Needless to say that several Chia's notions on tangible sexual issues could use a bit more research. For example, Chia makes reference to how ingesting semen "is at least as rational as buying vitamins" as it is a "treasure house" of vitamins and minerals. Anyone worth his salt knows that it only contains trace elements.
That statement alone makes me question just how accurate the rest of the book is. (Chia, of course, doesn't condone this sort of behavior, for you see, according to him, loss of this fluid can lead to baldness and premature death - hence the books whole stand point of retention and recirculating the energy contained within to other vital areas of the body.)
Where Chia really lost me, however, is when he suggested that women practicing exercises in this book "should keep [their] panties on to prevent any chi from draining out."