That the impact of your army may be like a grindstone dashed against
an egg—this is effected by the science of weak points and strong.
虛實, literally “the hollow and the solid,” is the title of chap.
VI. 碫 _tuan_ is the _T‘u Shu_ reading, 碬 _hsia_ that of the
standard text. It appears from K‘ang Hsi that there has been much
confusion between the two characters, and indeed, it is probable
that one of them has really crept into the language as a mistake
for the other.