A caravan traveled through the desert. The people in the caravan followed their guide on a long and dangerous trip to a treasure land.
Along the way, the people in the caravan became tired, confused, and discouraged. They told the guide that they could not go any further.
If they turned back, all their traveling would be wasted. The guide did not want the people to give up the journey. He knew that a wonderful treasure was at the end of the journey.
When the caravan had traveled more than halfway, a great city appeared. The guide told the people of the caravan that here was an opportunity to rest and be refreshed.
After they rested, the guide made the city disappear. He told the people that the city was nothing more than an illusion he had created to allow them to rest. He told them that their goal, the treasure land, is close.
Refreshed, the travelers continued on their journey.
The phantom city represents the teachings of the three vehicles the Buddha expounded in order to guide people toward enlightenment. The treasure land represents the one Buddha vehicle toward which people should ultimately aim.
~ From the Lotus Sutra, Chapter 7