Since ancient times, boundaries of shrines and other holy places in Japan have been marked off by sacred ropes called shimenawa. Mizuhiki is the custom - still followed today - of conveying sentiments ranging from congratulations to condolences by tying knotted designs in thin cords to seal the message. With our guest, knot scholar Miyuki Sekine, we look at the beauty that can be created by knotting a single cord, and explore the influences on Japanese design of old traditions connected with tying knots and ropes.