He believes the Leaving Cert in its current form should be scrapped immediately, the long school summer holidays are "a disgrace" and that classes should be half their current size.
Mark Patrick Hederman, abbot of Glenstal Abbey in Co Limerick, gives a ringing denunciation of our second-level system in his new book, The Boy in the Bubble.
In an interview with the Irish Independent this week he also revealed that Glenstal is to admit girls for the first time.
He said: "After 1,500 years of education the Benedictines have discovered that there are two species on the planet – men and women."
Girls will initially be introduced as day pupils in fifth and sixth year, but no date has yet been set for the start of co-education at the 80-year-old school.
He said allowing girls to attend as boarders would be difficult in the short term, because of building costs.
"In principle we would now favour a move towards co-education as a more balanced and appropriate educational milieu."
The abbot may no longer be principal of the exclusive Co Limerick school, but he has launched a broadside against the Irish education system in his latest book.
He believes that the current orthodoxy that 800 is an optimum number in second-level schools is deeply flawed.
"The Department of Education decided on that number at the same time that the Minister for Agriculture was proposing the same optimum number for pig farms."
The Benedictine Monk believes the full potential of every child is more likely to be happen in smaller schools and small classes with a maximum of 20 pupils.
Smaller class sizes may be possible in fee-paying schools such as Glenstal, but how could the Government possibly afford them in the free sector?
"There is no point in pretending that we are providing free education, if classes are huge and many students aren't getting any education at all.
"In a big class only a few students will be reached. It all depends on the teacher. He or she may just concentrate on the weaker students, and brighter children may be bored stiff.
"We are certainly training enough teachers to have smaller classes. It is much more important for schools to have small classes than expensive equipment such as computers, or magnificent halls."
The abbot says it is widely accepted that the Leaving Cert has failed, but criticises Ruairi Quinn for not replacing it immediately.
He takes no comfort from the fact Glenstal regularly finishes top of Leaving Cert points tables.
"The points system is no indication of how good an education is.
"The system is mind-numbing. It is the regurgitation in one single day of the year of material learned off by heart – such as facts about the stem of a plant. In an age when facts can be looked up on Google, it is an out-of-date exercise as ineffective as it is counter-productive."
He said it was absurd that success in an English Leaving Cert exam could be based on guesswork about which poet will come up.
"The job of most English teachers is to make such predictions accurately.
"You're a great teacher if you guess correctly, you're a dud if you don't.''
Abbot Hederman said the second-level system is still based on an early 20th Century factory model.
This sees schools as "assembly lines to provide children with chunks of knowledge necessary to work in a rigid hierarchical society where memory and obeying rules are all you need to be an efficient cog in the wheel''.
He said the current school year is still broken up according to farming cycles.
"The number of days taken as holidays in the summer is a disgrace.
"Of course, teachers love their holidays, but they come from a time when children had to work.''
The abbot believes that schools have to fire the creative imagination of students if our education system is to succeed. He advocates a greater engagement by pupils with the natural world.
"We should take children out into the country and use our coastline. They should be taken to the old estates that are dotted around the country.
"Having spent the morning being introduced to the natural world the afternoon can be spent expressing what they experienced. This could be in music or painting or literature.
"It can all be done in a much more dynamic way than the factory model, where they are sitting in the same clothes and the same rigid way all day."
Abbot Hederman believes he benefited from not going to school until age nine. He was educated at home in Co Limerick by his mother, and had no structured lessons.
"I was taught how to read and write, and that was it. It fed my curiosity.
"Because I was not told that I was in a particular age group I tended to think like an adult.
"When I eventually went to school I found the other students quite childish."
The monk is sceptical of claims that improved performance in science will save the education system. He says there should be a privileged place for imagination and the arts.
He believes imagination is being crowded out in the present curriculum.
"Our children have no time for dilly-dallying, no space for inner or outer explorations, no opportunity for dreaming. Every minute of every day is full up with learning.''
The Boy in the Bubble is published by Veritas.