The third of the Five Precepts undertaken by lay Buddhists runs: Kamesu micchacara veramani sikkhapadam samadiyami, "I undertake the course of training in refraining from wrong-doing in respect of sensuality." Some lay people who, usually for a specified period, undertake more than the usual five precepts, take this one in the stricter form: Abrahmacariya veramani..., which commits them, for the duration of the undertaking, to observe the same restraint as the monks.
With these, too, we are not further concerned, as their position is now obvious.
It is an undertaking by you to yourself, to do your best to observe a certain type of restraint, because you understand that it is a good thing to do. If you don't think it is a good thing to do, you should not undertake it.
If you do think it is a good thing to do, but doubt your ability to keep it, you should do your best, and probably, you can get some help and instruction to make it easier.
The only one we are concerned with here is the first, which deals with sexual intercourse.
Complete sexual continence is considered an essential feature of the monastic life.
The rules are voluntarily undertaken, and if a monk feels unable to live up to them, he is free to leave the Order, which is considered much more honorable than hypocritically remaining in the robe while knowingly infringing the rule.
There are four basic rules, infringement of which is termed Parajika or "Defeat," and involves irrevocable expulsion from the Order.
This is the third, further revised version of the original Sangha Guide on Buddhism and Sex published by the English Sangha Trust, Dhammpadipa, London NW3.
The greater part of it also appeared in the journal Sangha.
Firstly, in common with all the other precepts, it is a rule of training.