Throughout history, masking has allowed people to unmask inner psyches -- not all jovial.

Clowns from the Middle Ages and Renaissance were often portrayed as sinister.

This dark side endures. Professionals attribute coulrophobia -- fear of clowns -- to a negative encounter with an unfamiliar, overwhelming presence during childhood.

A clown's painted facial expression does not change, therefore cannot predict behavior that may confuse a child. The unsettling image has been perpetrated in literature, notably Stephen King's "It" and an entire genre of killer-clown films including "Killer Clowns."

Clown people have not always been happy, in or out of makeup. Emmett Kelly, America's famous clown-creator of "Weary Willie" perpetuated by his son and grandson, suffered clown-related personal problems. Grandson Paul Kelly, found guilty of murder, claimed Willie had taken over his personality.

Serial murderer John Wayne Gacy gained infamy as Pogo the Clown. Red Skelton's Freddie the Freeloader and other quasi-clowns experienced more downs than ups. Enrico Caruso broke hearts as the lovelorn Pagliacci -- smiling on the outside, crying on the inside -- in the opera by Leoncavallo.

Don't forget The Joker.

Despite positive reactions to Bozo, Clarabell and Ronald McDonald, some children and adults instinctively shy away from clowns. Ed Renner and his troupe have discovered one at FirstHealth; this staffer is warned of their approach and takes cover before the clowns appear on Wednesday afternoons.