The Buddha couldn't fully relate his new understanding of the universe, but he could spread the essential message of his enlightenment and guide people toward achieving the same understanding. He traveled from place to place teaching the four noble truths:
- Life is suffering.
- This suffering is caused by ignorance of the true nature of the universe.
- You can only end this suffering by overcoming ignorance and attachment to earthly things.
- You can overcome ignorance and attachment by following the Noble Eightfold Path.
The Noble Eightfold Path is a list of eight ideals that guide a person toward greater understanding of the universe. The eight ideals are:
- Right views
- Right intention
- Right speech
- Right action
- Right livelihood
- Right effort
- Right contemplation
On the surface, the eight ideals are incredibly vague -- they're open to almost any interpretation. Buddhist sects do view them differently, but generally speaking, Buddhists follow the path by approaching the world with compassion, patience and joy, and contemplating the universe through meditation. The fundamental goals are to cultivate morality (shila), meditation (dhyana) and wisdom (prajna).
Buddhists who achieve nirvana on their own become buddhas, awakened ones (this is different from "the Buddha," the specific buddha who was incarnated as Siddhartha). Like the Buddha, other buddhas gain omniscience when they are enlightened. Buddhists who achieve nirvana with the help of a buddha guide become arhats, people who are enlightened but not omniscient.
While nirvana is possible for any person, in most Buddhist sects only monks attempt to achieve it. Lay Buddhists -- Buddhists outside the monastic community -- strive instead for a higher existence in their next life. They follow the Noble Eightfold Path and help others, trying to accumulate good Karma. In this sense, they're working toward nirvana because they're setting up a future life in which they might achieve nirvana.