Buddhas and the highest level bodhisattvas attain the patience that leads to complete nirvana. They reach the state in which “The mind stays tranquil but is constantly observant. The mind is observant but constantly stays tranquil.” This patience is higher than the tolerance of non-arising of phenomena.
The patience that leads to complete nirvana can be compared to water that is completely still. The tolerance of non-arising of phenomena can be compared to water that is slightly rippling.
It takes careful observation to detect the rippling, or else one will not see it. The water can reflect clearly. When a lake has no waves, all the views are reflected on the water. It looks beautiful. But if you look closely, you will see ripples. The surface of the lake is not perfectly still. This is like the state of bodhisattvas who have attained the tolerance of non-arising of phenomena.
In the state of bodhisattvas with the patience that leads to complete nirvana, there is no rippling at all as “The mind stays tranquil but is constantly observant. The mind is observant but constantly stays tranquil.”
~ Based on Ven. Master Chin Kung's 2003 lecture series on the Amitabha Sutra