"Just try this some time. Take into your mind an image––somebody that you care for, some image that you would care to contemplate––and try to hold this image still in your mind. You will find that you are immediately thinking of other images, associated with the first; for the mind continues spontaneously to move. Yoga is the intentional stopping of this spontaneous activity of the mind stuff. It is an intentional bringing to rest of this continuous action.
"But why should one wish to do this?
"A favorite simile used in Indian discussions of this is that of the surface of a pond with its waves in action––a wind blowing over the pond and the waves moving. If you look at the surface of a pond moving in this way you will see the many reflections––many broken forms; nothing will be perfect, nothing complete; you will have only broken images before you. But if the wind dies down and the waters become perfectly still and clear, suddenly the whole perspective shifts and you are not seeing a lot of broken images, reflecting things round about. You are looking down through the clear water to the lovely sandy bottom, and perhaps you will see fish in the water. The whole perspective changes and you behold, not a multitude of broken images, but a single, still, unmoving image.
"This is the idea of yoga. The notion is that what we see when we look around, like this, are the broken images of a perfect form. And what is that form? It is the form of a divine reality, which appears to us only in broken images when our mind stuff is in action."