In the words of Yamaguchi sensei, The Square represents variety, yet this is quite an understatement. The square is the solid foundation on which the activity of the triangle and the circle depends. The triangle represents the mind that gives birth to movement. It is Intent reaching out and creating movement and form. The Circle is the manifest form created by that movement. The square is stabilization and creativity and it brings this process to its completion. It is the stabilization of movement through the balance of yin and yang.
The Japanese word for “Square,“ is Shikaku, or “Four corners.” Shikaku, however, can also mean “competency” or “mastery.” The triangle and the Circle represent direction and form, yet without the function of the square there is no power or effectiveness. The Square is Earth, or more specifically, “Mountain.” In the words of O-sensei, “Power is from the Earth, direction is from Heaven.”
The monk Takuan referred to mastery as Fudoshin, immoveable body/mind. He went on to explain that, “Immoveable mind is the mind that is constantly in motion.” In other words, although it is unshakeable it is never attached to or stuck on any one thing. O-sensei referred to it with the Shinto term Takemusu Aiki, usually interpreted as the continual and spontaneous creation of new forms.
Take is the continual interchange of yin and yang and Musu,is Musubi, harmonizing the forces of yin and yang. In order to do this, the master must be at home, in the center, between those forces, and freely balancing them. O-sensei referred to this ability as Ame no Uki Hashi ni Tateru, “Standing on the floating bridge of Heaven.”
Harmonizing the forces of yin and yang is to bring them under control. This was expressed by the founder as Bring your partner down (Osae) in the sign of the square. Osae is not only to physically bring someone down. It also means to calm things down, to gather ki inside and bring things to a state of harmony. The square represents the perfect balance of yin and yang represented by the Eight Powers.
In other words, the square is the endless source of variety and creativity. We should never be stuck in any one form or another, but rather we should allow the principle of Aiki to inform our feelings, thoughts, and movement. Rooted to the earth, the source of power, and looking to Heaven, or principle, for direction; this is the path towards Spiritual freedom.