history
From Li Shangyin's 《无题》 (Tang dynasty): 身无彩凤双飞翼，心有灵犀一点通。 灵犀 refers to a mythical rhino whose horn was said to contain a fine white line connecting both ends, symbol of telepathic understanding between lovers. Now extended to any kind of close mental rapport (teammates, old friends, collaborators).
culture
One of the most quoted love-poem lines in the Chinese language. In contemporary use, heavily applied to sports partners, band members, and long-married couples as well as romantic love.
