Sei (purity) is the ability to treat oneself and others with a pure and open heart. This is really the essence of tea training. This purity is not one of absolute cleanliness but one of pure heart. With a pure heart, harmony and respect can be realised. When the tea garden is cleaned, one’s heart and soul are also being purified. When one wears clean clothes this purity also exists. A pure heart is not ostentatious, but natural. Sen Rikyu's ideal of purity was the natural look of the garden after it was cleaned, with a few leaves from a tree fallen onto the freshly manicured moss.