One farmer says to me, “You cannot live on vegetable food solely, for it furnishes nothing to make bones with;” and so he religiously devotes a part of his day to supplying his system with the raw material of bones; walking all the while he talks behind his oxen, which, with vegetable-made bones, jerk him and his lumbering plough along in spite of every obstacle. – from Walden, by Henry David Thoreau

Over the years, many friends (and some strangers) have asked me why I am a vegetarian. Because I’ve been asked so many times, and because I have become somewhat weary of the ensuing conversation, I typically deliver a canned response: health reasons. Unfortunately, this is only a half-truth. I became a vegetarian for health reasons, but this is not the primary reason that I continue to remain a vegetarian today. If it were, I probably would have quit many years ago.

A good friend of mine, who is also a vegetarian, was once asked: “Don’t you ever crave a hamburger?” His response: “I’m a vegetarian, not a carnivore who does not eat meat.” Pithy, if slightly sarcastic, his words get to the heart of the matter.

Sustainable vegetarianism requires a fundamental shift in being, not just behavior. Being a vegetarian means more than simply not eating meat in the name of good health. It means shifting to a life-long practice of compassion. I know more people today who once were vegetarians than are vegetarians, and I think it is for this very reason. Health does not provide the motivational stick-to-itiveness that only compassion can.

When asked why he was a vegetarian, philosopher Alan Watts famously quipped, “because cows scream louder than carrots.” All eating involves killing, but it pays to be mindful of it, and Watts knew it. This is what true vegetarianism is all about. The first person to teach this to me was John Robbins.

I first met John Robbins in November, 2002, a month after my leukemia diagnosis. It was a rainy Saturday in San Francisco, and I’d flown up from Los Angeles to attend the Green Festival with my dad. Pale, anemic, and tired – I had just started my first trials of the leukemia medication Gleevec – I found a random seat in the conference hall and sat down to rest. Conferences can quickly wear you out, even more so when you already feel worn out to begin with. And at the time I sat down – only a few hours into the conference – I was more than ready to go home. Today, I’m glad that I didn't. Taking that seat dramatically changed my life.

Five minutes after I sat down, John Robbins, a vegan lifestyle advocate once heir to the ice-cream fortune of Baskin-Robbins, took the stage to talk about his latest book The Food Revolution. Robbins was eloquent, but even more than that, he was energetic and passionate. I quickly perked up. The Food Revolution was Robbins' second book; his classic Diet For a New America being his first. It was immediately clear that he had been studying, researching, and living the vegetarian lifestyle for a long time.

Within fifteen minutes I heard everything I needed to hear to convince me that I needed to become a vegetarian. Longer life-span. Lower incidence of cancer. More energy and better overall health. Only a month earlier, I had been knocking on death’s door. I knew I needed to make some changes, and felt that simply following “doctor’s orders” would not suffice. I needed something more, and Robbins was the first person to show me the way. I bought a signed copy of his book and never looked back. Much to the chagrin of my meat-eating relatives, I became a vegetarian only a few days before Thanksgiving. I’ve been a vegetarian for over ten years now, and have honestly never felt better.

But selfishness will only get one so far. One thing I quickly came to realize after finishing The Food Revolution was how intimately my health was tied to the health of my environment. This should have been obvious to me beforehand. My leukemia was caused by environmental factors – perhaps chemical, perhaps radiative – that to this day neither I nor my doctor cannot pinpoint. Good health is interdependent.

When I began studying Zen, I suddenly saw my vegetarian diet from a whole new perspective, deepening my understanding of this interdependence. The first of the Four Bodhisattva Vows espouses “saving all sentient beings.” The first of Ten Bodhisattva Precepts says “no killing.” As firsts, these promises are foundational and primary to all other Zen practice. It should come as no surprise, then, that most Zen Buddhists, particularly in Asia, are vegetarian. Perhaps nowhere in our lives do the effects of our decisions and our behavior have more impact on other living beings than in our diet. Vegetarianism is simply mindful recognition of this fact.

The recent wave of health-related documentaries – Super Size Me, Food, Inc., Forks Over Knives, Fat, Sick and Nearly Dead, etc. – that have streamed their way into thousands of homes courtesy of Netflix has done a fantastic job of educating Americans about the many perils of their diet. More and more people are “trying out” vegetarianism than every before. But, in a few years, we’ll have a great many more “used-to-be” vegetarians unless we can shift the public perception of vegetarianism from being about health to being about compassion. This is the only way to get people to stay vegetarian for the long term.

As for my part, I’ll stop saying that I’ll take a pass on the hamburger for “health reasons.” The real truth is that Alan Watts was right: cows really do scream louder than carrots.