The Face On Your Plate is a call to veganism from Jeffrey Moussaieff Masson, an American animal behaviourist, author and former psychoanalyst. Subtitled The Truth about Food, The Face on Your Plate clarifies many uncomfortable and unsavoury realities about consuming animal products, but allying his animal rights instincts with the environmental movement is Masson's masterstroke: this book could, quite literally, save the world.

Masson foregrounds his case in the negative ecological fallout of industrial farming. The arguments are sound: three quarters of the US's nitrous oxide (296 times more polluting than carbon dioxide) comes from agriculture; pigs and cattle excrete almost three times as much waste nitrogen than humans globally (in the US it is 130 times more); toxic chemical and animal runoff from factory farms has poisoned 173,000 miles of rivers and streams; land the size of seven football fields (often precious forested areas) is razed every minute to create room for farmed animals; 40 percent of all grain produced worldwide goes to feed livestock, not humans.

And the causal links are straightforward: nitrous oxide, along with methane and carbon dioxide, is a greenhouse gas which contributes to climate change; the waste products from irresponsible farming practices pollute water sources and damage ecosystems; rainforests act as carbon sinks - natural and vital temperature regulators to keep the planet healthy - we need them.

There is nothing new here, but Masson hopes it will spur meat-eating environmentalists to reconsider the link between farming and climate change. He admits to jumping on the environmental bandwagon recently, but as a marketing tool for veganism it is a very effective approach.

As a lapsed vegetarian I fear The Face on Your Plate will undermine my justifications for eating meat all over again. Masson's armaments are certainly plentiful and powerful. Early on he invokes the Holocaust, comparing its atrocities with those committed during meat production, an analogy repeated several times in the book. "The ability to imagine ourselves into the minds and bodies of "others" - whether humans we term different from us or the animals we use for our food - is of central importance because the failure to do so is precisely what led to the horrors of Auschwitz."

Academically speaking, The Face on Your Plate is not a difficult book to stomach, but the portrait of cattle, pigs and chicken bred in horrendous conditions for slaughter is harder to swallow. Even more disturbing, perhaps because it is less well known, is Masson's explanation of the animal cruelty involved in producing milk and eggs - the debeaking of chickens, the separation anxiety felt by dairy cows when their young are taken away. "It is much harder to cover up what animal flesh is," he says, "but if you were to ask the average person in England whether it is cruel to take milk or eggs, 90 percent or more would say no. If you explained it to them they still might not understand. I think if they saw it and perceived it with their own eyes, then it would be a different story."

Masson's own conversion to veganism indeed came through seeing dairy production facilities himself. Could we not just go organic? "Organic farming is definitely better for us, but it is not better for the animals. They get better food, but if you're on death row, do you really care what your last meal is?"
Masson, 68, was brought up a vegetarian in 1940s Hollywood. His Jewish parents studied Hinduism and followed the British mystic Paul Brunton. He went on to study Sanskrit at university, where he became a carnivore through "laziness", only reverting in the early 1990s while researching When Elephants Weep, the first of a string of works about the emotional lives of animals.
When still a vegetarian, he remembers César Chávez, the Mexican farm workers activist and a vegan, saying that it would be better to eat meat and give up dairy and eggs. "I think he was trying to shock me into recognising something," admits Masson now. "I would say the two are equally cruel." Back then, Masson chose to ignore Chávez's challenge. His Road to Damascus moment came much later when he was already in his sixties.

Ever since, he has been unable to comprehend how anyone could eat animal products. He has come to believe that otherwise compassionate humans can only eat their fellow animals through ignorance, expressed as denial - "one of the few concepts of modern psychology that I really do agree with". Denial is an unconscious mechanism that helps us live with unpleasant truths. Masson includes a chapter on this theory, exploring how ordinary folk, farmers, chefs, animal experts and philosophers can eat animal products because of the process of disengagement with what is on their fork. If we stop denying ourselves the full reality of what it is we are eating, Masson reasons, we couldn't eat it.

Masson calls this a "face on the plate" moment. His editor had one with tongue, as soon as she realised the clue was in the name. By the time we reach our teens, most people know that meat is meat, but we can still eat it by engaging in fleeting denial while choosing and eating food - and by not considering animals our equals. "If we have the capacity to imagine the suffering of an animal, we also have the power to refuse to allow ourselves to think about that suffering...We refuse to acknowledge, in a complete breakdown of our capacity for empathy, that they are entitled to the full happiness of which they are capable."

Masson is well acquainted with denial: he will eat cheese if someone has cooked it for him and doesn't want to cause a fuss. Unsurprisingly, he has received a lot of criticism for this admission, but says he doesn't have the same "visceral reaction" to a piece of cheese that he does to a piece of meat. "I think mozzarella is a glorious thing from the point of view of taste. The only thing that stops me eating it is my intellectual recognition that it causes suffering, and that doesn't always trump my taste buds."

Masson hopes that vegans will give this book to their non-vegan friends and the community will grow, but it took him so long to have his vegan epiphany this might be a slow process. Yet, from an evangelising start, his approach softens as the book goes on, acknowledging that eating organic and having meat free days will reduce animal suffering, albeit to limited extent.

After animal welfare and environmental concerns, the third reason for going vegan is health. Masson his confident his vegan diet is what keeps him healthy, but he avoids all vices. In health terms, there are as many anti-vegan arguments as there are pro, and you cannot be a healthy vegan without taking supplements.

The most illuminating chapter is "The Fishy Business of Aquaculture". Many people who call themselves vegetarians eat fish and myths abound about how little fish feel. Masson blows these theories out of the water. We share 85 percent of our DNA with certain fish, but perhaps they are easier to swallow because we do not recognise them as being "like us" in the same way we do a cow or a pig.

Our appetite for fish is so great it is possible our exploitation of the oceans has already reached the point of no return.
All readers will be moved by this sensitive illustration of the emotional capacities of animals. Overcoming our daily denial of this is a trickier prospect.

The Face on Your Plate: The Truth about Food is published by Norton, £15.99

Saturday 20 June - an afternoon with Jeffrey Masson, sponsored by The Vegan Society.
2.30-5pm
Dragon Hall, Covent Garden, London, WC2B 5LT.
Refreshments will be served and there will be a book signing following the talk. All welcome.

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