Today's Daily Dharma from Tricycle explains "monkey mind."
Stream of Thoughts
We tend to be particularly unaware that we are thinking virtually all the time. The incessant stream of thoughts flowing through our minds leaves us very little respite for inner quiet. And we leave precious little room for ourselves anyway just to be, without having to run around doing things all the time. Our actions are all too frequently driven rather than undertaken in awareness, driven by those perfectly ordinary thoughts and impulses that run through the mind like a coursing river, if not a waterfall. We get caught up in the torrent and it winds up submerging our lives as it carries us to places we may not wish to go and may not even realize we are headed for.
Meditation means learning how to get out of this current, sit by its bank and listen to it, learn from it, and then use its energies to guide us rather than to tyrannize us. This process doesn’t magically happen by itself. It takes energy. We call the effort to cultivate our ability to be in the present moment “practice” or “meditation practice.”
-- Jon Kabat-Zinn, Wherever You Go, There You Are; From Everyday Mind, a Tricycle book edited by Jean Smith