If you can one day renovate yourself, do so from day to day. Yea, let there be daily renovation.
茍日新,日日新,又日新。
Original text (Chinese)
Source, in full
According to the Great Learning (ch. 2, sec 1) in the Book of Rites, these words were engraved on Tang's bath tub. Translation: James Legge, The Chinese Classics, vol. 1 (1861), p. 225. Chinese: Sheng Dai; Si Zi, "大學", in Donald Sturgeon (ed.) 禮記 ['Book of Rites'], Chinese Text Project