When we are beginners many thoughts arise very quickly in our minds, like mountain streams running down a mountain very fast; there is movement of thoughts arising and becoming. The first thoughts come like a waterfall, so fast. If we practice meditation every day–I know there are beginners here, people just starting, young people–this kind of meditation, gradually extending the period of meditation, five, ten minutes and so on, eventually we will have fewer thoughts arising. It is more like water that has left the mountain and becomes like a meandering stream bubbling by; the thoughts slow down a bit. Eventually the water opens out into the great ocean. There will be a complete absence of thoughts. The thoughts have not been eliminated, per se; they have been transformed into transcendent wisdom.
Quoted from the book Precious Teachings, written by Khenpo Karten Rinpoche, under the chapter “Sunyata, Essence of Mind,” page 98 in the print version, page 105 in the PDF version.
