Literary;
九 here means 'extreme/utmost' rather than the number nine. Familiar from
庄子·
列御寇:
夫千金之珠，必在九重之渊 'a thousand-gold pearl must lie in a deep nine-fold abyss'. Also the courtesy name of Song philosopher
陆九渊 (Lu Jiuyuan, founder of the
心学 'Mind School').
