When the Buddha was first asked about precepts, he told his first disciples (who were fairly advanced, grounded practitioners), “You all know what’s right and what’s wrong. Do what’s right and avoid what’s wrong.” This worked quite well with them, but later, when more uneducated and more out of touch(?) disciples came the Buddha had to get more specific to help them step outside of their own particular blind spots.
In general, the guideline that works quite well is this: If it makes your heart brighter, it’s probably okay. If it makes your heart darker, then avoid it. If you can’t tell, probably best to avoid it.
(Repenting of the Ten Evil Actions)
I now deeply repent of sexually improper thoughts and behavior.
사음한 큰 죄 오늘 참회합니다.