Green and purple, lingering in my heart, means: expressing my heart's incomparable yearning for pursuit.
Later, Cao Cao quoted a sentence in "Short Songs": Qingqing Zitiao is leisurely in my heart, but only for the monarch, and I have been pondering it so far. It means Tsing Yi scholar (because all students in the Han Dynasty wore blue clothes), which is what I admire in my heart. Because of you, I think about how to attract you. These poems express Cao Cao's thirst for talents.