That's a tough one. Every man between 18-40 years of
age have broke that law. Hands up (men) if you never
committed adultery in your thoughts. Last nite on
TV, "Ancient sexual relations" Bible rules. They mention
this character name Origen who decided to, er, separate himself
from his sexual bits(self castration) and be free from temptation and let everyone
know that it was impossible for any hank-panky to be going on.
What ever the reason that was a little extreme.
But here again in the minds of Medieval people, Ancient people
believed that there was something mystical in our thoughts, our
thoughts held mystical powers.
Remember the verse states, just thinking about it you have committed
adultery, not that this may lead too adultery. And what about
the single friends, fornication.