A kōan is a story, dialogue, question, or statement used in the practice of Zen.
It’s a challenge — intended to provoke a "great doubt" and test a student's progress.
Zen is a school of Mahayana Buddhism originating in China.
It emphasizes rigorous self-restraint, meditation-practice, insight into the nature of mind and nature of things, and the personal expression of this insight in daily life, especially for the benefit of others.
In Zen practice, an ensō (円相, "circular form") is a hand-drawn circle made in one or two uninhibited brushstrokes
It expresses a moment when the mind is free to let the body create.