In the mid-19th century, the Tibetan Buddhist master Nyala Pema Dündul composed a poem in which he gave an account of a recent visionary experience. In this short work, he recalls waking up one morning and beginning his usual daily practice, focused on Avalokiteshvara, the bodhisattva of compassion. Suddenly his perception shifted, and instead of having to consciously visualize the deity he was able to see and speak with Avalokiteshvara directly, as if the bodhisattva were truly present. Serving as something of a tour guide, Avalokiteshvara showed Nyala Pema Dündul around various hell realms, where he observed people being tortured by demons with animal heads. These torments, Avalokiteshvara explained, were the inevitable consequence of having eaten meat in a previous life. Perhaps not surprisingly, Pema Dündul tells his readers that he emerged from his vision shaken, lamenting the fact that he himself had eaten meat. “Let the three jewels be my witness!” he writes, “In the past, ignorance and habit have led me to eat the flesh of beings. . . . From today on, may the thought of eating meat never even enter my mind! If I do eat it, may the three jewels punish me!”

Nyala Pema Dündul was not alone in his concern about meat eating. In fact, a meatless diet in Tibet was far more common than might be expected. To date, I have identified more than 110 individual lamas—religious teachers—who made the decision to give up meat and who were active prior to the Chinese invasion of the 1950s. Given the fact that Buddhist history in Tibet has spanned 1,300 years, 110 may not seem like a large number. But it represents only those individuals I could identify by name—there must have been many others who are as of yet untraceable. Whether or not one should eat meat was a real, active debate in premodern Tibet, and vegetarianism was a not infrequent response.

And yet the simple fact that vegetarianism existed in Tibet is almost unknown today. Indeed, contemporary Tibetan Buddhists—both Tibetan and Western—tend to assume that vegetarianism was a non-issue. Time and again I have been told that researching the history of Tibetan vegetarianism is pointless, as the diet simply did not exist. Contained in this assumption, moreover, is an argument against adopting vegetarianism today. Like followers of other traditions, Tibetan Buddhists often look to examples set by previous masters to guide their own conduct. So it is not surprising that contemporary Buddhists often answer the question of why they eat meat by pointing to revered masters from the past who ate meat. Vegetarianism, following this view, is a modern innovation foreign to traditional Tibetan Buddhism and should therefore be regarded with suspicion.

But this is not true. Vegetarianism was not only present in pre-communist Tibet; it was in fact a significant aspect of Tibetan religious practice. It is not that vegetarianism ever became the norm—even among the devout, it always seems to have been a minority practice. But it was a significant and vocal minority. Furthermore, these vegetarian lamas came from all the major Buddhist lineages in Tibet, from all regions, and from all time periods. Some were relatively minor figures, but others were among the most important masters of their day and remain well known centuries later. Dolpopa, the 14th-century founder of the Jonang lineage, became a vegetarian when he took full ordination at 22. Jikten Gonpo and Taklung Tangpa, founders of the Drigung Kagyu and Taklung Kagyu in the 12th century, were both lifelong vegetarians, as was Ngorchen Kunga Zangpo, 15th-century founder of the Ngor Sakya. At least seven members of the Karmapa lineage have been vegetarian. The 19th-century master Shabkar Tsokdruk Rangdrol, his contemporary Patrul Rinpoche, the early 20th-century Bon polymath Shardza Tashi Gyaltsen, and many others were all staunch vegetarians.

If someone is motivated by desire to eat the flesh of beings, then butchers will seize animals such as yaks or sheep and sever their minds from their bodies. How can those who consume meat and blood as food be followers of the Buddha? Such people pridefully consider themselves to be benefiting beings and protecting the weak, but their actions contradict the precepts! Meat is nothing but the cause of amassing terrifying sins. — Shardza Tashi Gyaltsen, The Faults of Eating Meat

Sometimes the texts not only tell us that an individual became vegetarian but also describe the circumstances surrounding their conversion, though they are not all as colorful as Nyala Pema Dündul’s account. Shabkar was walking the pilgrimage circuit in Lhasa, the capital of Tibet, when he came across the carcasses of many sheep and goats, slaughtered to feed the city. A wave of compassion rose up in him, and he immediately went before the Jowo, the statue of Shakyamuni Buddha that stands at the heart of the Jokhang, the holiest temple in Tibet. Looking up at the revered statue, Shabkar vowed never to eat meat again. He was so adamant in his vegetarianism, he tells us, that patrons would remove all the meat from their homes before he would visit, afraid he would be upset at the mere sight of it. The Nyingma visionary Jigme Lingpa had a similar experience, seeing a row of sheep tied up and awaiting slaughter. A powerful sense of compassion arose in him—more powerful, in fact, than in any practice he had done previously. Decades later, he described the experience as the “most important event of my life.”

Related: Tibet’s Vegetarian Debate

If all these masters were united in their aversion to meat, however, they were also united in the belief that a vegetarian diet was deeply unhealthy. According to Tibetan medicine, the human body has three major humors: wind, bile, and phlegm. If these are balanced, then the person is healthy. If the humors become unbalanced, then illness will arise. In this view, meat was understood to keep the wind humor in check. Even many vegetarians believed that without meat the wind humor would become too strong and the body would become weak and jittery. And yet some Tibetans consciously rejected meat even when they anticipated that this rejection would have a direct and negative impact on their health. The biography of Jikten Gonpo relates that at the end of his life he was offered a medicinal broth made with dried and powdered yak lungs to prolong his life. A lifelong vegetarian, he refused it and died shortly thereafter. Similarly, Ngorchen Künga Zangpo’s biography states repeatedly that his vegetarian diet left him weak and feeble. Both texts were written by close disciples, and it is possible to detect a hint of frustration that their masters privileged vegetarianism over their own health and time with their students. For these writers, as well as just about every other Tibetan I’ve read, vegetarianism was perceived as an unhealthy ascetic practice that could lead to illness and even premature death.

So why do it? Why did all these masters willingly choose a diet that they felt was bad for them? The answer is compassion; for many Tibetan religious leaders, compassion was and is the central point of all religious practice. In the words of Shardza Tashi Gyaltsen: “Compassion is the essence of all of the Buddha’s teachings.”

Compassion can mean many things, even among Buddhists. But most Tibetan authors I have come across agree that practicing compassion includes trying to reduce the suffering of “others,” a category that unambiguously includes animals. There is a stream of Euro-American philosophy that regards animals as irreducibly different than us, devoid of a soul and therefore without any moral standing at all. Descartes, for instance, famously described animals as mere machines, a view that he used to justify vivisection and other violent practices. By contrast, Tibetan authors make clear that animals are sentient beings with minds and emotions. They are not necessarily as intelligent as humans, but they can experience physical and emotional pain. Furthermore, they are able, at a minimum, to anticipate the near future and so experience deep fear when they know that pain is imminent.

All these ideas are captured in a passage from Jigme Lingpa’s autobiography:

Having now become animals, your fathers, mothers, siblings and friends from previous lives tremble with fear in the butcher’s sinful hands, tears streaming from their eyes, and panting for breath. In that state they wonder what to do. Alas, there is no refuge! There is nowhere to go! Thinking that, right now in this place, they may be killed, their urgent suffering is great. In such a state, like one approaching a terrifying pit of hellfire, their body is turned upside down, their muzzle is tied up, and their eyes move wildly with lights shining forth. What they see is their stomach being opened up. With their feet perpendicular to the ground, they are set on the path to the next life without even a quiver.

—trans. Geoffrey Barstow

For Jigme Lingpa, animal suffering is real. And since animal suffering is real, humans who claim to practice compassion have an obligation to reduce it— meaning that they should stop eating meat.

Beyond pointing out the causal connection between eating meat and animal suffering, Jigme Lingpa, Shardza Tashi Gyaltsen, and other vegetarian lamas also rebutted counterarguments. One of the most important objections was the question of what the Buddha himself said about eating meat. As meat apologists pointed out, the Tibetan canon includes sutras in which the Buddha explicitly allows monks to eat meat, as long as the meat in question adheres to the “rule of threefold purity.” This rule states that monks may eat meat as long as they have not seen that the meat was killed specifically for their own consumption, have not heard that it was killed specifically for them, and have not even suspected that it was killed specifically for them. Since meat with threefold purity had not been killed specifically for the consumer, the person eating it was insulated from the responsibility for (and therefore the karmic repercussions of) the sinful act of killing.

For the most part, lamas sympathetic to vegetarianism accepted that the rule of threefold purity was an authentic teaching of the Buddha. Rather than attacking the rule directly, therefore, they typically argued that it did not apply in a Tibetan context. Specifically, they argued that the rule of threefold purity only applies to shravakas, those who practiced certain forms of Buddhism that Tibetan lamas generally regarded as lower than their own, Mahayana path. Sakya Pandita explains this in his Distinguishing the Three Vows: “Shravakas may eat meat that has threefold purity. . . . In the Mahayana, meat is forbidden. Eating meat, it is taught, causes rebirth in the lower realms.” To support this argument, Sakya Pandita and others pointed to canonical Mahayana texts such as the Lankavatara Sutra and the Mahayana Mahaparinirvana Sutra, both of which state unequivocally that the rule of threefold purity was taught only for those who practice the vehicle of the shravakas. Because the Mahayana path takes compassion as its central focus, these sutras argue, the rule of threefold purity no longer applies and monks may not eat meat.

When I think of the suffering that meat eating brings, I cannot bear the pain and anguish I feel within my heart. — Nyala Pema Dündul, Song of Advice for Giving Up Eating Meat

A second argument raised by meat apologists was that their Tantric practice meant they could eat meat without worry; here they usually invoked either the idea that Tantric practitioners should actively transgress social norms or the fact that Tantric rituals require meat offerings. In response, authors sympathetic to vegetarianism usually asked their readers to realistically assess their own level of spiritual attainment before doing anything potentially unethical. “You should think like this,” Jigme Lingpa advised his students in his teaching Engaging the Path to Enlightenment. “‘In a tantric context, it’s great if someone has given rise to the power of concentration, so that he is not tainted by obscurations and is able to benefit beings through a connection with their meat and blood. But I do not have this confidence.’”

Overall, Jigme Lingpa and other vegetarian lamas seem to have regarded such pro-meat arguments as mere intellectual sophistry. Instead of trying to find a way to justify eating meat on religious grounds, they wrote, practitioners should first recognize and accept that it was sinful and then do their best to give it up. This did not necessarily mean that they demanded full vegetarianism among their students. But they did want students to reflect honestly on what they were eating and then change their diet to whatever extent they felt they could. The ideal was for someone to become fully vegetarian: Shabkar recalls with some pleasure that he converted 300 of his disciples to full vegetarianism. But if an individual felt this was impossible, then they could at least try to reduce their consumption. Tibetan biographies are replete with examples of individuals who gave up meat for one day a month or one month a year. The important point was to stop kidding yourself about the consequences of your diet and then do your best, even with the understanding that giving up meat was unhealthy.

Where does this leave us today? For one thing, it’s surely time to put to rest the old idea that all Tibetan lamas throughout history ate meat. Rather than a settled issue, the question of meat eating was the subject of ongoing, contentious debate, for while many lamas certainly did eat meat, many others did not. It is not only inaccurate to suggest otherwise, but it denigrates the effort these masters put into practicing and promoting what was, to them, a difficult and dangerous diet.

Related: Tibetan Medicine: Ancient Wisdom for Modern Health and Healing

In fact, the idea that vegetarianism was unhealthy was the only argument that could convince firmly vegetarian lamas to either eat meat themselves or to permit it among their disciples. But this argument rested on two pillars: the difficulty of finding non-meat foods, and medical assumptions about the role of meat in human health. And both of these pillars are cracking at present. Far more food options are available than was the case just a decade or two ago, even in remote nomadic pasturelands. And the incursion of Western medicine has resulted in shifting assumptions about the medical necessity of meat. Because of these changes, many Tibetans are now willing to accept that one can be perfectly healthy as a vegetarian. Some have even told me that they now think vegetarianism is healthier than eating meat!

This changing attitude has helped opened up cultural space for vegetarianism, allowing for the emergence of a powerful vegetarian movement in contemporary Tibet. Many monasteries that used to serve meat, for instance, are now vegetarian. In 2007 I visited Dzogchen Monastery in the eastern Tibetan region of Kham. The monks ate their meals together from three large vats of soup. One of these vats was vegetarian; the other two had meat. When I returned in 2012, the pots were still in use, but all three were now vegetarian. Similarly, it used to be difficult to find vegetarian meals in restaurants, but today restaurants commonly carry entire menus of vegetarian food, even outside of the main cities and towns. Seeing this rise in vegetarianism’s popularity, Chinese companies recently began to market tofu and other “fake meat” snacks directly to Tibetans.

Some people have suggested that this movement is more connected to external influences than internal ones. For instance, a 2013 article by the French Tibetologist Katia Buffetrille quoted a comment by Jamyang Kyi, a Tibetan blogger, that contemporary vegetarianism is a “fad inspired by Chinese Buddhists and Western vegetarians.” Claims like this, however, ignore the long history of vegetarianism in Tibet itself—one that honors traditional Tibetan concerns about animal suffering, now seeing fresh life in a context in which vegetarianism is considered a reasonable and healthy diet.