But now, after publishing 29 books, the son of a "restless" Paris-born gem merchant and apprentice to a spiritual guru is moving to Berlin to be close to his pediatrician wife Leila's elderly mother.
Before he leaves, Mr Masson is giving away most of his personal library.
Unitec Institute of Technology in Auckland and Waikato University will each receive 1500 animal-related books.
He has been in discussion with various Holocaust centres around the world about receiving his comprehensive collection on the topic.
The buyers of his Karaka Bay home will be left 2000 books to help fill the many metres of custom-fit bookshelves.
Auckland independent used bookseller Jason Books will get the rest.
"At first, the thought of getting rid of my books was wrenching - like getting rid of a part of myself," Mr Masson said.
"I've used all of them, they tell my life story. In a way, I define myself through my books." But the decluttering has been a surprisingly cathartic process.
"It's been one of the most freeing experiences I've ever had," the father of three said.
Ever the philosopher, he has concluded that private libraries are "wrong" - that books "should be like education, and available to one and all".
However, he has not been able to part with all of them.
Around 800 of his favourite books will travel with him back to Europe.
They include the collected works of Sigmund Freud in 24 volumes, despite being fired in 1980 from his esteemed position overseeing the Sigmund Freud Archives for declaring that the founding father of psychoanalysis was wrong to say child abuse was fantasy.
"Even though I'm not a Freudian, it makes up so much of my background."
He is also keeping every book of his favourite author, Primo Levi, and even his most hated, Steven Pinker's The Better Angels of Our Nature.
"I can't stand that book but if anyone gets in an argument with me about it, I can pull it out and say, 'Look at what he said!"'
On the shelves
Masson's likes
• Sigmund Freud: The first three volumes of the Standard Edition in 24 Volumes
• Primo Levi: Survival in Auschwitz
• Janet Gotkin: Too Much Anger, Too Many Tears: A Personal Triumph Over Psychiatry
• Jean Amery: At the Mind's Limits: Contemplations by a Survivor on Auschwitz
• Daniel Ellsberg: Secrets
... and dislikes
• Steven Pinker: The Better Angels of our Nature
• Richard Herrnstein and Charles Murray: The Bell Curve
• Carl Jung: Collected Works
• E.O. Wilson: Sociobiology
• Janet Malcolm: In the Freud Archives
