When Max Eisen disembarked from a train at the Auschwitz concentration camp in May 1944, he said a "flick of the wrist" quickly determined who would live and who would die.

His mother, siblings and grandparents were signalled to head to the left, which meant they were going to the gas chambers.

Eisen, who was 15-years-old at the time, along with his father and uncle, were told to go to the right, which meant they were selected for slave labour.

"We were totally disoriented, it was the middle of the night," Eisen recalled. He said he still remembers the sounds and "the smell of burning flesh.”

"There was a very fast selection on the platform where our family was split," the 87-year-old told CTV's Canada AM on Monday. 

Eisen was the sole member of his family to survive the concentration camp.

He details the back-breaking labour, the death march, his journey to Canada and the painful path of healing in his new memoir "By Chance Alone."

Before he died in Auschwitz, Eisen's father told him that, if he survived, he must "tell the world what happened here."

Eisen, who has dedicated the last 22 years of his life to educating others about the Holocaust, says he struggled with the painful memories he had to recall to put his story down on paper.

"You're put into a work unit -- it was hard labour, 10 to 12 hours a day living on a 300 calorie liquid diet," he said. "It's excruciating hunger, and your body was fast disappearing right in front of your eyes."

Eisen said surviving required some preparation, some skills, "and a lot of luck."

His luck came after he suffered a serious head injury at the hands of an SS guard, and he was sent to a hospital instead of the gas chambers.

After he was operated on, Eisen said he was given a lab coat and put in charge of sterilizing medical instruments in the surgical ward.

"I was no longer working outside under these psychopathic killers," he said. "I had more of a structured life for the next few months," he said.

Eisen eventually immigrated to Canada, and he had no intentions of returning to the site of the former concentration camp. But at the request of his granddaughter, the two visited Poland in 1998 for the March of the Living, a yearly, three-kilometre walk from Auschwitz to the former Birkenau camp that takes place on Holocaust Remembrance Day. The walk is a silent tribute to all Holocaust victims.

"It was a very difficult journey for me and for her," he said. "I was going back to a place…where my entire family was murdered.

"I had to introduce my granddaughter to the spirits of the family she didn't even know," he said.

Eisen has since returned Auschwitz upwards of 18 times with various groups.

"It is unbelievable how people could build such a destructive piece of machinery," he said. "People need to see this, so we don’t repeat the same mistakes ever again."