One of the great tragedies of human life is the possibility of one human being enjoying an activity that makes another human being suffer.  The suffering of the latter can easily happen without the former knowing it.  The former might even think that the latter is taking the same enjoyment that the former is.   In the kingdom of heaven, it will be different:  our field of knowledge and sensitivity will be much wider, so that it will not be possible to take any action without feeling everything there is to be felt about it’s consequences.   This will amount to de facto obedience to the golden rule.  The only things that will happen will be those that cause universal rejoicing.