Dr. Hall is an informative and understanding obstetrician and even though books on doing it abound he's got something when he says that too many fall into essentially three categories: ""the pornographic, the flippant and the pedantic."" His own chief appeal is clarity and modesty; without venturing into the darker recesses of the libido, without moralizing or proselytizing, he spells out the biology of coupling -- the positions, techniques and timing which will prolong and intensify pleasure for both men and women, married or single, liberated or old-fashioned. He believes in variety and experimentation as antidotes to sexual boredom but nothing very outre -- no group sex, no fancy equipment, no elaborate seduction routines and forget about the Kama Sutra. All of it presupposes two loving, heterosexual partners who are willing to give in order to get. A responsible and wholesome guide -- say, for the adolescent ready to take the plunge.