The Enso is circle made using a calligraphy brush that is supposed to be emblematic of one's inner state or enlightenment. To make the circle perfect is extremely difficult. As you can see by this beautiful example brushed by Torei Enji, who was a disciple of the famous monk Hakuin, you cannot tell if the circle was brushed clockwise or counter clockwise. It looks so perfect it is almost fake. Like all Japanese arts there is a subtleness where its power or greatness can only be revealed after years of study. In Shodo, anyone can make a circle after a few lessons, but the circle will have something missing. Only a true master can put ki into the brush stroke which is called bokki. Bokki expresses the calligraphers inner state and conveys a state of grace, calmness and power that can only attained after many years of training.
Aikido is a true Japanese art because its power is hidden in its subtlety and is lost on the uninitiated. From the outside looking in most think, "Oh it looks so easy" or "It's fake" only to find it to be extremely difficult and only after years of experience and exploration can one come to see the true power of Aikido. One's inner state is conveyed in the way one does Aikido.
Aikido's power, like in all Japanese arts, takes years to master and even more to understand. Its power lies in subtleness and its subtleness is part of its power. Think of it like gravity. Gravity is subtly acting on us at every moment, but we can't feel it despite the fact that we intellectually know it works. The moment when we get to feel it is too late as we succumb to power and hit our heads. Aikido's power is that subtle. In order to understand its subtlety one has to practice for many many years. That is why Miyamoto Musashi said, "It takes 1000 days to forge the spirit and 10,000 to polish it." I guess we better get back to training.