杳之若日,偏如滕兔
Dark then like the sun, slant like a surging rabbit
杳 distant and out of sight, gloomy; dim; dusky, dark and quiet, disappear, remote and out of sight, obscure, dark, mysterious, deep.
之 "then" (之 knows multiple uses as a particle, in some cases with no particular meaning. Translating it by "then" is just to avoid not mentioning it), up to.
若 as if, like if, assuming, similar.
日sun.
偏 slanting, leaning.
如 like, as if, such as.
滕 to surge, water bursting forth.
兔 rabbit.
This phrase is a typical example of a totally obscure text when one has not been given any clue to decipher such sentences. To understand what seems not only a total paradox but also two statements which do not seem to have any connection, one has to remember that change was the cornerstone of old practices. Indeed "Martial without change, a waste of the study of the Art"*.