The Five Vehicles (Pa?ca-yāna) consist of Human Vehicle, Heavenly Vehicle, Sāvaka Vehicle, Pacceka-buddha Vehicle and Bodhisatta Vehicle. The last three are referred to as the Super-mundane conditions or Lokuttara-dhamma, its doctrines are comparatively profound and difficult to learn; the former two, Human and Heavenly Vehicles, are the Worldly conditions or Loka-dhamma. The Worldly Conditions or theories are easy to study and should be followed by the common people. So it was named Popular Buddhism by the predecessors. The main contents of the Popular Buddhism are the Five Precepts (Pa?ca-sīlā) and Ten Good Acts or Ten Virtuous Deeds (Dasa-Kusalāni). The former involves abstaining from killing, stealing, sexual misconduct, lying and drinking intoxicants. Buddhism holds that these immoral conducts must be strictly prohibited. Hence the term Five Precepts. The Ten Good Acts, based on the Five Precepts, regulate the Three Kammas (body, speech and mind) in a total of ten ways. Pertaining to the body kamma, there are three items: avoidance of killing, stealing, sexual misconduct; pertaining to the verbal kamma are four items: avoidance of lying, slandering, rude speech and foolish babble; and to the mental kamma are three items: avoidance of covetousness, hatred and ignorance. These are Ten Good Acts, and the opposite is known as the Ten Bad Acts or Ten Unwholesome Deeds.
人乘、天乘、聲聞乘、緣覺乘、菩薩乘這叫五乘。其中后三種叫出世間法,教理深奧,比較難學;前二人天乘教是世間法。世間法是世人易學而能夠做到的也是應該做到的,前人名之為人間佛教。人間佛教主要內容就是:五戒、十善。五戒是:不殺生、不偷盜、不邪淫、不妄語、不飲酒。佛教認為,這類不道德的行為應該嚴格禁止,所以稱為五戒。十善是在五戒的基礎上建立的,約身、口、意三業(yè)分為十種。身業(yè)有三種:不殺、不盜、不邪淫;口業(yè)有四種:不妄語欺騙,不是非兩舌,不惡口傷人,不說無益綺語;意業(yè)有三種:不貪、不嗔、不愚癡。這就叫十善,反之就叫十惡。