When perception is stronger than mindfulness, we recognize various appearances and create concepts such as "body," "cat", "house," or "person". . .
On some clear night, go outside, look up at the sky, and see if you can find the Big Dipper. For most people that is a familiar constellation, easy to pick out from all the other stars. But is there really a Big Dipper up there in the sky? There is no Big Dipper up there. "Big Dipper" is a concept. Humans looked, saw a certain pattern, and then created a concept in our collective mind to describe it. That concept is useful because it helps us recognize the constellation. But it also has another, less useful effect. By creating the concept "Big Dipper" we separate out those stars from all the rest, and then, if we become attached to the idea of that separation, we lose the sense of the night sky's wholeness, its oneness. Does the separation actually exist in the sky? No. We created it through the use of a concept. Does anything change in the sky when we understand that there is no Big Dipper? No.
--Joseph Goldstein, Insight Meditation
