When the hour of dire need draws nigh Keep the faculty of effort alive in you by a little gratuitous exercise every day. That is, be systematically ascetic or heroic in little unnecessary points, do every day or two something for no other reason than that you would rather not do it, so that when the hour of dire need draws nigh, it may find you not unnerved. William James, Principles of Psychology wisdomneed
Truchet Tiles Truchet tiles are square tiles decorated with patterns that are not rotationally symmetric. When placed in a square tiling of the plane, they can form varied patterns, and the orientation of each tile can be used to visualize information associated with the tile's position within the tiling. Wikipedia en.wikipedia.org The Tiling Patterns of Sebastien Truchet and the Topology of Structural HierarchyWang tiles graphicsart