70 Now the fact that quotations from the Art of War , acknowledged or otherwise, are to be found in so many authors of different epochs, establishes a very strong anterior to them all⁠—in other words, that Sun Tzǔ’s treatise was already in existence towards the end of the 5th century BC . Further proof of Sun Tzǔ’s antiquity is furnished by the archaic or wholly obsolete meanings attaching to a number of the words he uses. A list of these, which might perhaps be extended, is given in the Hsü Lu ; and though some of the interpretations are doubtful, the main argument is hardly affected thereby. 71 Again, it must not be forgotten that Yeh Shui-hsin