As far as dharma art is concerned, we begin just to be with object perceptions, without accepting or rejecting. It’s like a frog sitting in the middle of a big puddle, with rain constantly falling on it. The frog simply winks its eyes at each raindrop that falls on it, but it doesn’t change its posture. It doesn’t try either to jump into the puddle or to get out of the puddle. That quality is what is symbolized by a sitting bull. So the frog becomes a sitting bull.
From “The Process of Perception” in True Perception: The Path of Dharma Art by Chögyam Trungpa, page 75