佛教常识_为什么一部分佛教徒要出家？

Why do some Buddhists need to renounce the lay life?
为什么一部分佛教徒要出家？

Before answering this question, it is necessary to explain the Buddhist doctrine of Pañca-yāna (Five Vehicles). Yāna means a vehicle which can carry passengers to their destinations, far or near. It is used here as a metaphor of the Buddha's teachings. The doctrine of Pañca-sīla (Five Pre-cepts: abstaining from taking life from sentient beings, taking things not given, sexual misconduct, false speech, the use of intoxicants) enables the practitioners to be reborn in the human world, so it is called Manussa-yāna (human-vehicle). The doctrine of Dasa-kusalānī (Ten meritorious acts—avoidance of the ten evils: 1. killing, 2. taking things not given, 3. sexual misconduct, 4. irresponsible speech, 5. speech inciting discord, 6. harsh speech, 7. licentious talk, 8. covetousness, 9. anger and 10. heterodoxy, i.e. denial of the doctrine of cause-effect) enables the practitioners to be reborn in heaven, so it is called Deva-yāna (heavenly vehicle). The doctrine of Four Noble Truths (ariya-sacca, namely, the truth of Suffering, of the Origin of suffering, of the Extinction of suffering, and of the Eight-fold Path leading to the extinction of suffering) enables the people to discard wrong views (diṭṭhānusaya or micchā-diṭṭhi) such as ego-illusion (atta-diṭṭhi), eternity-belief (sassata-diṭṭhi), annihilation-belief (uccheda-diṭṭhi), etc., and defiled thought (micchā-saṅkappa) such as greed (lobha), hatred (dosa) and delusion (moha), finally, to attain nibbāna(enlightenment). So it is called sāvaka-yāna (voice-hearer vehicle). Voice means the Buddha's teachings. Those who hear the Buddha's teachings, realize the Four Noble Truths and are free from sufferings are called sāvakā. Before the advent of the Buddha-Dhamma, people who independently came to the realization of the Theory of Paṭiccasamupāda (Dependent Origination) and obtained emancipation, but were unable to speak out their self-enlightened truth were called Pacceka-Buddha (Independently Enlightened One). That is why the Dhamma of Dependent Origination is called the vehicle of self-enlightenment (pacceka-yāna). The doctrine of Six Perfections (cha pāramitā) enables the practitioners to act in the way of Bodhisatta, to undergo the countless difficulties and hardships in cycles of birth and death, and to finally attain Buddhahood. So this teaching is called the vehicle of Bodhisatta (Bodhisatta-yāna).
要说明这个问题，先要谈一谈佛教的五乘教法。乘就是车子，能运载行人到远近不同的目的地，借以比喻教法。五戒的教法（戒杀、盗、淫、妄、酒的五条戒）能令修持者得生人间，叫做人乘。十善的教法（不犯十恶即是十善。十恶是指：一、杀；二、盗；三、淫；四、妄语；五、两舌，即挑拨离间；六、恶口，即粗恶伤人的言语；七、绮语，即邪淫言语；八、贪；九、嗔；十、邪见，即否认因果的见解。）能令修持者得生天界，叫做天乘。四谛的教法，能令人断除见惑（我见、常见、断见等错误见解）和思惑（对世间事物而起的贪嗔痴等迷情），证得涅槃，叫做声闻乘。“声”是言教的意思，听闻佛的言教，悟四谛之理而得到解脱的人叫做声闻。在没有佛法的时代，有人独自悟到缘起之理而得到解脱，但他不能把自己悟到的真理说出来，这种人叫做独觉，因此十二因缘法叫做独觉乘。六度的教法，能令修持者行菩萨道，经过无数世的难行苦行，最后达到佛的果位，叫做菩萨乘。