i thought to myself... what if all the humans on earth meditated simultaneously? could we change the universe? then i recalled this story, about the chant "om mani padme hum".
The teacher had two disciples, who both undertook to perform a hundred million recitations of the mantra of Chenrezi, OM MANI PADME HUNG. In the presence of their lama, they took a vow to do so, and went off to complete the practice.
One of the disciples was very diligent, though his realization was perhaps not so profound. He set out to accomplish the practice as quickly as possible and recited the mantra incessantly, day and night. After long efforts, he completed his one hundred million recitations, in three years. The other disciple was extremely intelligent, though perhaps not as diligent, because he certainly did not launch into the practice with the same enthusiasm. But when his friend was approaching the completion of his retreat, the second disciple, who had not recited very many mantras, went up on the top of a hill. He sat down there, and began to meditate that all the beings throughout the universe were transformed into Chenrezi. He meditated that the sound of the mantra was not only issuing from the mouth of each and every being, but that every atom in the universe was vibrating with it, and for a few days he recited the mantra in this state of samadhi.
When the two disciples went to their lama to indicate they had finished the practice, he said, 'Oh, you've both done excellently. You were very diligent, and YOU were very wise. You both accomplished the one hundred million recitations of the mantra.