It’s from the beautiful, beautiful book Bluebeard, and I think I first heard it first (as with many such things) from Matt Webb:

“The team must consist of three sorts of specialists, he says. Otherwise the revolution, whether in politics or the arts or the sciences or whatever, is sure to fail.

The rarest of these specialists, he says, is an authentic genius – a person capable of having seemingly good ideas not in in general circulation.

“A genius working alone,” he says, “is invariably ignored as a lunatic.”

The second sort of specialist is a lot easier to find; a highly intelligent citizen in good standing in his or her community, who understands and admires the fresh ideas of the genius, and who testifies that the genius is far from mad.

“A person like this working alone,” says Slazinger, “can only yearn loud for changes, but fail to say what their shaped should be.”

The third sort of specialist is a person who can explain everything, no matter how complicated, to the satisfaction of most people, no matter how stupid or pigheaded they may be. “He will say almost anything in order to be interesting and exciting,” says Slazinger.

“Working alone, depending solely on his own shallow ideas, he would be regarded as being as full of shit as a Christmas turkey.”