Sixty years is really a number form of all of nature expressed. Sun, moon, and stars comprise the three lights. Spring, Summer, Fall, and Winter comprise the four seasons. Wood, water, fire, earth, and metal comprise the five phases. Combine the three lights, four seasons, five phases, Three times four times five, and we get sixty years. Sixty years is a combined number of complete nature revealed. In other words, nature is reborn once every sixty years. Gensokyo will resurrect this year. (from Phantasmagoria of Flower View, Shikieiki's scenario)