This is the entire spiritual life, Ananda, that is, good friendship, good companionship, good comradeship. When a monk has a good friend, a good companion, a good comrade, it is to be expected that he will develop and cultivate the Noble Eightfold Path.
A man traveling across a field encountered a tiger. He fled, the tiger after him. Coming to a precipice, he caught hold of the root of a wild vine and swung himself down over the edge. The tiger sniffed at him from above. Trembling, the man looked down to where, far below, another tiger was waiting to eat him. Only the vine sustained him. Two mice, one white and one black, little by little started to gnaw away the vine. The man saw a luscious strawberry near him. Grasping the vine with one hand, he plucked the strawberry with the other. How sweet it tasted!
If you want to understand the causes that existed in the past, look at the results as they are manifested in the present. And if you want to understand what results will be manifested in the future, look at the causes that exist in the present.
Delusions, errors and lies are like huge, gaudy vessels, the rafters of which are rotten and worm-eaten, and those who embark in them are fated to be shipwrecked.
But if you do not find an intelligent companion, a wise and well-behaved person going the same way as yourself, then go on your way alone, like a king abandoning a conquered kingdom, or like a great elephant in the deep forest.
Don't believe a teaching just because you've heard it from a man who's supposed to be holy, or because it's contained in a book supposed to be holy, or because all your friends and neighbors believe it. But whatever you've observed and analyzed for yourself and found to be reasonable and good, then accept that and put it into practice.