The Connection Between the Two Entities
On the very eve of Buddha's death, the Buddha states that "the eating of meat extinguishes the seeds of Great Kindness".
According to the Buddha in the Angulimala Sutra, since all beings share the same "dhatu" (spiritual principle or essence) and are intimately related to one another, killing and eating other sentient creatures is tantamount to a form of self-killing and cannibalism. The sutras which inveigh against meat-eating include the Nirvana Sutra, the Shurangama Sutra, the Brahmajala Sutra, the Angulimala Stura, the Mahamegha Sutra, and the Lankavatara Sutra, as well as the Buddha's comments on the negative karmic effects of meat consumption in the Kama Sutra. The eating of birds and fish was permissible because these are not considered to be sentient creatures.
"The reason for practicing dhyana and seeking to attain samadhi is to escape from the suffering of life, but in seeking to escape from suffering ourselves why should we inflict it upon others? Unless you can so control your minds that even the thought of brutal unkindness and killing is abhorred, you will never be able to escape from the bondage of the world's life...
After my parinirvana in the last kalpa different ghosts will be encountered everywhere deceiving people and teaching them that they can eat meat and still attain enlightenment...How can a bhikshu, who hopes to become a deliverer of others, himself be living on the flesh of other sentient beings?" - Lord Buddha (Surangama Sutra)
However, it should be understood that not all Buddhist adhere to the vegetarian diet, according to various Buddhist traditions and practices worldwide.
The Buddha had also declared that meat could be eaten. In the Jivaka Sutra...
"meat should not be eaten under three circumstances: when it is seen or heard or suspected (that aliving being has been purposely slaughtered for the eater); these, Jivaka, are the three circumstances in which meat should not be eat, Jivaka! I declare there are three circumstances in which meat can be eaten: when it is not seen or heard, or suspected (that a living being has been purposely slaughtered for the eater); Jivaka, I say these are the three circumstances in which meat can be eaten."
Reverend Thompson encourages everyone to practice vegetarianism when at all possible.