In the ancient meditation instructions, it is said
at the beginning thoughts will arrive one on top of another, uninterrupted,
like a steep mountain waterfall.
Gradually, as you perfect meditation,
thoughts become like the water in a deep narrow gorge,
then a great river slowly winding its way down to the sea,
and finally the mind becomes like a still and placid ocean,
ruffled by only the occasional ripple or wave.
-Sogyal Rinpoche