During the late Sui Dynasty, rebel leader Li Mi was already a diligent scholar when serving as a minor official. One day, while riding an ox, he hung a bag containing the *Book of Han* on its horn, gripping the reins with one hand and reading with the other. Duke Yang Su of Yue saw this and told his son Yang Xuangan, "I can see that Li Mi's insight and bearing are far beyond yours." Xuangan took these words to heart and befriended Li Mi.
In 613 AD, during the Sui Dynasty, Yang Xuangan plotted rebellion while Emperor Yang was away on a campaign against Goguryeo. He secretly summoned the strategist Li Mi for advice. Li Mi offered three strategies: the best was to march swiftly to Ji Prefecture near modern Beijing, cutting off the emperor's retreat; the middle was to seize Chang'an, as only the mediocre Wei Wensheng guarded it, depriving the emperor of his rear base; the worst was to stay in Luoyang, where victory was uncertain. Li Mi warned, 'If you choose the lower path, the outcome cannot be foretold.'
Yang Xuangan, however, adopted his inferior strategy, ultimately losing to the Sui Dynasty general Yuwen Shu and being captured himself.
"Zu" means "worthy." Later, the idiom "Not Worth Caring About" came to describe something unworthy of attention, indicating contempt.
Source: *Old Book of Tang*, "Biography of Li Mi"
Meaning of the Idiom: Later, the Chinese idiom "不足为意" came to describe how something unworthy of attention indicates contempt.