Furthermore, among some schools of Buddhism, there has been some debate with regard to a principle in the monastic discipline. This principle states that a Buddhist monk cannot accept meat if it comes from animals especially slaughtered for him. Some teachers have interpreted this to mean that when the recipient has no knowledge on whether the animal has been killed for him, he cannot accept the food either. Similarly, there has been debate as to whether laypeople should be vegetarian when adhering to the five precepts. Though vegetarianism among Theravādins is generally uncommon, it has been practiced much in East Asian countries, as some Mahāyāna texts, such as the "Mahāparanirvana Sūtra" and the "Laṅkāvatāra Sūtra", condemn the eating of meat. Nevertheless, even among Mahāyāna Buddhistsand East Asian Buddhiststhere is disagreement on whether vegetarianism should be practiced. In the "Laṅkāvatāra Sūtra", biological, social and hygienic reasons are given for a vegetarian diet; however, historically, a major factor in the development of a vegetarian lifestyle among Mahāyāna communities may have been that Mahāyāna monastics cultivated their own crops for food, rather than living from alms. Already from the 4th century CE, Chinese writer Xi Chao understood the five precepts to include vegetarianism.