If the enlightened could miraculously enlighten all instantly,
they would done so already.
In the mean time, the miracle of enlightenment arises
from realising the Dharma through diligent study and practice.
Once, a layman named Kevaddha told the Buddha that the city of Nalanda was nearby, full of people, many of whom admired him, and that if any of his disciples could perform a miracle, they would have greater admiration for him. He then asked if the Buddha could request a disciple to do so. Despite being asked thrice, the Buddha rejected his appeal. After all, the Buddha doesn’t encourage the performing of ‘street magic’ just to boast or please the populace. What more essential was to develop one’s mind and to guide others to do the same. On another occasion by a river, an emaciated ascetic with long thick hair glanced at the Buddha sarcastically, before crossing it on its surface. Seeing this, a disciple of the Buddha asked if he could see him do the same. The Buddha replied that he would show him the worth of the feat instead. When a ferryman came towards the Buddha, he asked him how much one paid him to cross the river. The answer was ‘half a masaka’, a coin of very low value. The Buddha remarked that the ascetic’s miracle was worth only that doable with half a masaka, while he had mortified his body over a long time just to master that. It would had been worthier to use the time for the well-being of others.
However, this does not mean that the Buddha and his disciples were incapable of, or never performed any miracles at all, though he did forbid insensible miracles which served no useful purpose. As recorded in the Mahaparinibbana Sutta, the Buddha once came to the swelling River Ganges. Some were looking for a raft, and others binding reeds to form one. The Buddha, as swiftly as a strong man stretches or flexes his arm, vanished from where he was with his retinue of monks and remanifested on the other shore. Commenting on those who have yet to cross, he said, ‘When they want to cross the sea, the lake or the pond, people make a bridge or raft, the wise have crossed already.’ In short, the Buddha had mass-teleported himself and the monks across the river in the blink of an eye! This is surely more efficient than walking on water! This was done for practical reasons of not being able to find transport, and it was an opportunity to teach. The late fashioning of a bridge or raft represented the belated creation or search of a means to cross the water, which represented the sea of suffering, to reach the other shore, which represented liberation. The Buddha was emphasising that wisdom is the true and speedy vehicle needed to cross over suffering.
In a related story, a ferryman refused to take the Buddha across a river because he did not have the fare to pay. To his amazement, the Buddha simply disappeared from the bank and reappeared on the opposite. When King Bimbisara heard of this incident, he issued an edict to allow all ascetics in his country to be ferried for free. Once again, the Buddha displayed his supernormal powers only as a last resort. Miracles by themselves might amaze, while not necessarily leading the amazed to realise the Dharma. They might distract their witnesses from the Dharma instead, who might be attracted only to learn how to perform such miracles. One of the most famous of miracles that only the Buddha could do, was the Twin Miracle. He would levitate into the air and sprout the opposing elements of fire and water from his upper and lower body simultaneously (followed by from his left and right), and in reversed directions. This he did on two occasions – once, to humble his proud clansmen, so as to open their minds to listen to the Dharma with reverence, and once, when some other teachers sought to promote their ‘superiority’ by showing off their miracles. As many other incidents would attest, the Twin Miracle is really just the tip of the iceberg of the extraordinary feats the Buddha was capable of!
As for the miracle where a certain person gives [Dharma] instruction in this way:
‘Direct your thought in this way, don’t direct it in that.
Attend to things in this way, don’t attend to them in that.
Let go of this, enter and remain in that':
this is the miracle that… appeals to me as the highest and most sublime.
– Sangarava Sutta
The Buddha’s Skilful Use of Supernormal Powers