"You've taken from each of them something that can never be replaced. You've taken from them their ability to trust people. You've taken their ability to form and keep meaningful relationships. You've taken from them their confidence, their self-esteem," he said.
"Each will, with time and support, find ways of dealing with that but none of that will ever truly go away; it's become a part of who they are.
"Every day for them is a little darker than the one before - even their happiest days. They'll wonder throughout their lives why that is, they'll wonder and be frustrated with all the people around them who can't see what's happening to them.
"That's what you did. It's not the touching, it's the scars that you left them with."
The first incident took place on April 24 when the man hung out with the group of youngsters, providing alcohol and cannabis for them.
When a 15-year-old girl was on her own outside, he pounced.
He hugged her, tried to kiss her and touch her breasts but she pulled away.
"You weren't going to take no for an answer at that stage," Judge Thomas said.
"You held her tight and continued kissing her neck... she pleaded for you to stop and eventually you did."
He stooped even lower just hours later, when he climbed on top of a 13-year-old girl who he found asleep on the couch.
"She woke to find you lying on her, with your hand down her pants," the judge said.
The following week the defendant repeated the pattern of sexual offending against two more teens.
He disputed the fact that his actions had been premeditated or that he had deliberately given the girls cannabis to overcome any resistance to his advances.
But Judge Thomas roundly rejected his explanation.
"Part of your reason in giving the girls alcohol and cannabis must have been to more easily facilitate your offending, to more easily create a sexual opportunity," he said.
The only credit the defendant received was for his late guilty plea, which saved the victims and their families the trauma of having to give evidence at trial.