In modern times, we know lust has measurable physiological effects and if persons have informed consent, they may be allowed to freely choose how to manage their own minds. Jesus gave a good caution in an age when very little,
apparently, was known by human beings about
the physiology of lust. I do not believe
we should close the question and sit in judgment
on lustful thoughts. I do believe lust should
be seen as a part of human experience which should be bridled.
May we learn from Jesus' caution and move on
with continuing respect for the seriousness of
the question.