We are not fit to lead an army on the march unless we are familiar
with the face of the country—its mountains and forests, its pitfalls
險, defined as 坑塹 (Ts‘ao Kung) or 坑坎 (Chang Yü).
and precipices,
阻, defined as 一高一下.
its marshes
沮, defined as 水草漸洳者.
and swamps.
澤, defined as 衆水所歸而不流者.