The teaching of the sexual tantras all come down to one point. Although desire, of whatever shape or form, seeks completion, there is another kind of union than the one we imagine. In this union, achieved when the egocentric model of dualistic thinking is no longer dominant, we are not united with it, nor am I united with you, but we all just are. The movement from object to subject, as described in both Eastern meditation and modern psychotherapy, is training for this union, but its perception usually comes as a surprise, even when this shift is well under way. It is a kind of grace. The emphasis on sexual relations in the tantric teachings make it clear that the ecstatic surprise of orgasm is the best approximation of this grace.
~ Mark Epstein