In regards to eating meat

[Monica]

Moreover, of the great spiritual teachers throughout history- only ONE advocated for vegetarianism. That was Mahavira. Buddha didn't talk about it. Laozi didn't talk about it. Jesus didn't talk about it. I wonder why that is?

Jesus

"What are the sins we must shun, that we may never more see disease?" And Jesus answered, "It was said to them of old time "Thou shalt not kill", for life is given to all by God, and that which God has given, let not man take away. For I tell you truly, he who kills, kills his brother. And from him will the Earthly Mother turn away and Satan will have his dwelling in his body. And the flesh of slain beasts in his body will become his own tomb. He who kills, kills himself and who eats the flesh of slain beasts, eats the body of death".

full text: Essene Gospel of Peace

Buddha

"You must teach people to put an end to killing and brutal cruelty. If one is trying to practice meditation and is still eating meat, he would be like a man closing his ears and shouting loudly and then asserting that he heard nothing."

"If a man can control his body and mind and thereby refrains from eating animal flesh and wearing animal products, I say he will really be liberated."
~ The Buddha
From the Surangama Sutra

"In his final teachings before he physically left this earth, the Buddha foresaw that a situation would arise in the future where those speaking in his name would pervert his Doctrine and encourage meat consumption. So here, in this great Nirvana Sutra, he lays down his last will and testament on the matter: in no circumstances should one eat meat or fish " nor animal corpses, found in the jungle, for instance " nor even accept from a donor a meal which contains an abundance of flesh-foods. The very contact of other food with meat is deemed defiling and requires purification of the food by water. It is quite evident from all this that the Buddha in no way condoned the eating of meat and was keen for his monastic and lay followers to abjure the uncompassionate practice of meat eating and follow the pure path of vegetarian Mahayana. In this, we would be wise and benevolent to follow him."

- Dr. Tony Page
Buddha - Self: The "Secret" Teachings of the Buddha in the Mahaparinirvana Sutra, Vol. 2

"The Buddha's teaching leads us to the realization that we must always strive to harm no sentient being, human or nonhuman, whether or not it is in our selfish interest to do so...The beginning of mindful eating is the realization that eating meat is not about the meat-eater; it is about the animals who are tormented and killed."
~ Norm Phelps
The Great Compassion: Buddhism & Animal Rights

"The eating of meat extinguishes the seed of great compassion."~
The Buddha
Mahaparinirvana Sutra

"Ultimately the case for shunning animal flesh does not rest on what the Buddha allegedly said or didn't say. What is does rest on is our innate moral goodness, compassion, and pity which, when liberated, lead us to value all forms of life. It is obvious, then, that willfully to take life, or through the eating of meat indirectly to cause others to kill, runs counter to the deepest instincts of human beings."
~ Roshi Philip Kapleau
To Cherish All Life


"There are three ways of killing that we, as Buddhists, have to restrain: either by directly killing, indirectly killing, or rejoicing to see others be killed. Not only does this apply to human life, it should be also extended to all living beings."

~ Zen Master Thich Thanh Tu
Buddhism for Beginners

"The eating of meat cannot in any way be considered to be helpful to the practice of the dharma, neither can the slaughter of animals be considered to be consistent with the Buddhist teachings of compassion (metta , ahimsa , and karuna ), of loving kindness, or of the nature of the evocation of the enlightenment-mind. The cruelties associated with the slaughter of the animal kingdom for human consumption, the pain, fear, and distress suffered by the animals in the entire process of being fattened for butchering, as well as the environmental disasters wreaked upon our planet through the meat industry, are very well documented, and should be understood by all who claim to be developing bodhicitta, or who wish to."
~ Bodo Balsys
Ahimsa : Buddhism and the Vegetarian Ideal

"Meat eating and a compassionate religion do not go hand in hand."
~ Bodo Balsys
Ahimsa : Buddhism and the Vegetarian Ideal

"One of the greatest obstacles to the birth of bodhichitta in our minds is our craving for meat."
- Shabkar Tsogdruk Rangdrol
Food of Bodhisattvas: Buddhist Teachings on Abstaining from Meat

from http://www.purifymind.com/SB32.htm

"The Buddha said time and time again in the sutras such things as: "My followers should give up all evil actions that directly or indirectly injure others." One may disregard his words; one may consciously lead others to commit evil in provisioning oneself with meat. One may think, "There are always skillful means in the sutras and tantras that counteract the evil so that I shall still be pure of stain." And one can let oneself off the hook by telling oneself that there are substances to be placed into the animals' mouths and words that can be whispered in their ears and impressed upon their minds so that they will not remain in the lower realms. But to do all this reveals a complete failure to grasp the meaning of the Buddha's teaching. It is a perversion of the Dharma."

- Shabkar Tsogdruk RangdrolFood of Bodhisattvas: Buddhist Teachings on Abstaining from Meat

"Buddhism cannot be true to itself until Buddhists resolve their ambivalence toward nonhuman animals and extend the full protection of their compassion to the most harmless and helpless of those who live at our mercy in the visible realms."

~ Norm Phelps
The Great Compassion: Buddhism & Animal Rights

Yet more books on Buddhism/Zen and vegetarianism/compassion:

Vegetarianism and Zen Practice by Sensei Sevan Ross

Ahimsa: Buddhism and the Vegetarian Ideal by Bodo Balsys

Pythagoras

"Beware O mortals, of defiling your bodies with sinful food! There are cereals, fruits, sweet vegetables and herbs which the flame can render palatable and mellow. Nor are you denied milk, nor honey. The bountiful earth offers you an abundance of pure food and meals obtainable without slaughter and bloodshed."

More spiritual teachers who were veg:

Paramahansa Yogananda (I would personally put this great master on the level of a Jesus or Buddha)

Mahatma Gandhi

Confucius

List of famous vegetarians

Gautama Buddha[66](pp11–88)[102](pp17–21)[157](pp21–23)[179](pp50–57)[106][182][nb 21]
Krishna[106]
Jiddu Krishnamurti[188][189]
Mahavira[66](pp19–28)
A. C. Bhaktivedanta Swami Prabhupada[66](pp173–180)[152](pp56–60)
Rama[106]
Swami Satchidananda[194]
Rabindranath Tagore[197]