Swordsmanship can be divided into three spheres;
The advantage of the heavens
The advantage of the Earth
The combination of the earth and the heavens (manipulated by man)
This is the secret of Hitotsu-tachi......Tsukahara Bokuden (early 1500's)
"The way of the mountain echo is the spirit of standing in the center of the connection between the ki of heaven and the ki of the earth"....Osensei (1930's)
Both men were known to have extradorninary -weirdly potent- power according to the norms of their day-over four hundred years apart.