The essay describes how sexual ethics are teleological in nature. The consequences of incest are down the road in succeeding generations as far congenital disease go. The injustice of theft is immediate. The teleological nature of sexual ethics makes them prone to disputations and variations in different cultures. Various sexual behaviors are discussed from anal sex to voyeurism. The strong influence of conditioning is stressed and the means of how conditioning works pointed out. Pavlov is fact; Freud's subconscious notion is superstition. Sexual pleasure is the extreme opposite of pain. The sub-topic of pain is viewed as unnecessary and even inimical to human health. The essay starts with a preface followed by a chapter on pain, then behaviors followed by two chapters on conditioning and a final concluding chapter.