Those concentric or spiral circles in the layers of the tree trunk are very suggestive. Since I first saw them there, remotely, in the subject Biology as a teenager, I was impressed. Now that you present them in your photograph, that vision has renewed me. Your association with ying and yang (by the way, one of my favorite icons; I identify with it on facebook) is very appropriate; although I also imagine the face of a one-eyed owl (haha!). The photo almost allows us to feel the hardness and roughness of the wood. Thank you, @velimir.