Where there is an ongoing relationship of caring. Where there is a sense of humor. Where there is a sense of mutual mercy. Where there is a sense that God has given sex to you . . . there is nothing livelier. But when it is merchandised as a commodity for instant gratification, there is nothing deadlier than sex.
I have a hunch that the last institution around at this moment which has a high doctrine of sex is the Church. We still believe sex is a good gift from God but it needs to be in context of a committed, loving, continuing relationship.