(from The Tibetan Book of Living and Dying by Sogyal Rinpoche)
Asanga was one of the most famous Indian Buddhist saints, and lived in the fourth century. He went to the mountains to do a solitary retreat, concentrating all his meditation practice on the Buddha Maitreya, in the fervent hope that he would be blessed with a vision of this Buddha and receive teachings from him.
For six years Asanga meditated in extreme hardship, but did not even have one auspicious dream. He was disheartened and thought he would never succeed with his aspiration to meet the Buddha Maitreya, and so he abandoned his retreat and left his hermitage. He had not gone far down the road when he saw a man rubbing an enormous iron bar with a strip of silk.
Asanga went up to him and asked him what he was doing. "I haven't got a needle," the man replied, "So I'm going to make one out of this iron bar." Asanga stared at him, astounded; even if the man were able to manage it in a hundred years, he thought, what would be the point?
He said to himself: "Look at the trouble people give themselves over things that are totally absurd. You are doing something really valuable, spiritual practice, and you're not nearly so dedicated." He turned around and went back to his retreat.
Another three years went by, still without the slightest sign from the Buddha Maitreya. "Now I know for certain," he thought "I'm never going to succeed." So he left again, and soon came to a bend in the road where there was a huge rock, so tall it seemed to touch the sky.
At the foot of the rock was a man busily rubbing it with a feather soaked in water. "What are you doing?" Asanga asked.
"This rock is so big it's stopping the sun from shining on my house, so I'm trying to get rid of it." Asanga was amazed at the man's indefatigable energy, and ashamed at his own lack of dedication. He returned to his retreat.
Three more years passed, and still he had not even had a single good dream. He decided, once and for all, that it was hopeless, and he left his retreat for good. The day wore on, and in the afternoon he came across a dog lying by the side of the road. It had only its front legs, and the whole of the lower part of its body was rotting and covered with maggots.
Despite its pitiful condition, the dog was snapping at passersby, and pathetically trying to bite them by dragging itself along the ground with its two good legs.
Asanga was overwhelmed with a vivid and unbearable feeling of compassion. He cut a piece of flesh off his own body and gave it to the dog to eat. Then he bent down to take off the maggots that were consuming the dog's body. But he suddenly thought he might hurt them if he tried to pull them out with his fingers, and realized that the only way to remove them would be on his tongue. Asanga knelt on the ground, and looking at the horrible festering, writhing mass, closed his eyes. He leant closer and put out his tongue....
The next thing he knew his tongue was touching the ground. He opened his eyes and looked up. The dog was gone; there in its place was the Buddha Maitreya, ringed by a shimmering aura of light.
"At last," said Asanga, "why did you never appear to me before?"
Maitreya spoke softly: "It is not true that I have never appeared to you before. I was with you all the time, but your negative karma and obscurations prevented you from seeing me. Your twelve years of practice dissolved them slightly, so that you were at last able to see the dog.
Then, thanks to your genuine and heartfelt compassion, all those obscurations were completely swept away, and you can see me before you with your very own eyes. If you don't believe that this is what happened, put me on your shoulder and try and see if anyone else can see me."
Asanga put Maitreya on his right shoulder and went to the marketplace, where he began to ask everyone: "What have I got on my shoulder?"
"Nothing," most people said, and hurried on. Only one old woman, whose karma had been slightly purified, answered: "You've got the rotting corpse of an old dog on your shoulder, that's all."
Asanga at last understood the boundless power of compassion that had purified and transformed his karma, and so made him a vessel fit to receive the vision and instruction of Maitreya.
Then the Buddha Maitreya, whose name means "loving kindness," took Asanga to a heavenly realm, and there gave him many sublime teachings that are among the most important in the whole of Buddhism.
Sogyal Rinpoche, The Tibetan Book of Living and Dying (San Francisco, CA: Harper, 1992), pp. 191-192.
For more about Sogyal Rinpoche and his works, visit Rigpa. (Sogyal Rinpoche gave the name "Rigpa" to his work and to the vehicle he was developing to serve the Buddha's teaching in the west.)