Denying the "orchestrated" abuse which took place in child care homes across Scotland should be a crime, an inquiry has heard.
A former resident of Smyllum Park in Lanark made the claim before the Scottish Child Abuse Inquiry in Edinburgh on Tuesday.
He described his time at the orphanage as a "Holocaust of developmental trauma" and said Scotland has to "face up" to its past.
The witness, who lived in the Catholic-run home between 1961 and 1965, said his head had been left "spinning" after reading an article suggesting abuse claims about such places were exaggerated.
He added: "What was happening there was a crime against humanity. It was orchestrated.
"It went on for years. I think it was a Holocaust of developmental trauma, inflicted upon thousands of children over decades.
"In Germany it's a crime to deny the Holocaust and I would like it to be a crime for academics to deny these years and years of abuse.
"Scotland has to face up to this - if you don't know your own country's history, you don't know anything."
Now in his sixties, he said he still has a recurring nightmare about his time there and wakes up screaming.
According to him, the nuns were "quick to aggression" and "quick to anger", describing constant physical and mental abuse.
The witness added: "Being in a place like that was about survival, if you came out there alive you were lucky - many didn't."
He then referenced a mass grave near to Smyllum, thought to have hundreds of children from the home buried in it.
The witness said he has "blocked out" many memories of his time in care as a way of coping with the abuse.
One occasion included being taken outside of the orphanage with what he was told was a potential foster carer.
He said: "I remember being taken out by him in a car, being taken to his house and thinking: 'This is wonderful - maybe I'll have a real dad and live in his nice house.'
"I remember being taken to the bedroom and then I don't remember anything at all."
His next recollection was that it was morning and being taken back to the home, which was formerly run by Daughters of Charity of St Vincent de Paul.
Colin MacAulay QC, counsel to the inquiry, put it to him that nuns described the home as a "happy place", but this was rejected.
Fiona Young, who waived her right to anonymity, moved to the orphanage in 1973 when she was aged five or six.
She told how she got visions of blood whenever she entered the playroom after witnessing a violent assault on one of the boys.
The inquiry heard he had continued to play on a piano after being told to stop when the attack happened.
Ms Young said: "The nun grabbed him by the back of the hair and slammed his head on the piano again and again.
"He was bleeding. Every time I went in there I just saw blood.
"I don't remember seeing him again after that."
She also told how she was bullied by the nuns and other residents because she was Protestant.
Ms Young, who left the home in 1975, added: "We were told we weren't God's special children."
The inquiry continues on Thursday.
Copyright (c) Press Association Ltd. 2018, All Rights Reserved.