The music that can deepest reach,
And cure all ill, is cordial speech.

Ralph Waldo Emerson
Ralph Waldo Emerson (1803-1882) American essayist, lecturer, poet
Essay (1860), “Considerations by the Way,” The Conduct of Life, ch. 7
    (Source)

Based on a course of lectures by that name first delivered in Pittsburg (1851-03).