Despite being a cheesy song, "Ebony and Ivory" is factually incorrect.
Black notes and white notes on a piano keyboard are not in perfect harmony. They are, rather, discordant. Play a random black note and a random white note on a piano and see what I mean. The sound produced will not necessarily be pretty.
However, in combination with each other, black keys and white keys can make beautiful melodies.
I suppose that's the irony (among many others) of this country.