Traditional Japanese aesthetics developed from the country's period of self-isolation and were influenced by Chinese ideas, Buddhism, and Western concepts. Japanese art focuses on "form and design" as well as living functionality and spiritual simplicity. Key aesthetic principles include wabi-sabi (appreciation for impermanence and imperfection), miyabi (elegance and refinement), and shibui (simple, subtle beauty). Additional concepts are iki (originality), jo-ha-kyu (gradual tempo changes), yugen (mystery), and enso (calligraphic circle representing absoluteness).