Effects of non-ejaculatory intercourse
If a man has intercourse once without spilling his seed, his vital essence is strengthened. If he does this twice, his hearing and vision are made clear. If three times, all his physical illness will disappear. The fourth time he will begin to feel inner peace. The fifth time his blood will cerculate powerfully. The sixth time his genitals will gain new prowess. By the seventh his thighs and buttocks will become firm. The eigth time his entire body will radiate good health. The ninth time his lifespan will be increased.
- from the Canon of Taoist Wisdom collected by Emperor Tang