We can learn much about a society from its signs whether they announce weekend events at the Dance Palace or warn: “Speed Limit. Radar Enforced.”

“The sign brings customers,” wrote the French fabulist Jean de La Fontaine (1621-1695), but sometimes signs can make it appear that the merchant has changed her mind. Take this pairing of signs on the door of the Busy Bee in Inverness Park. To be fair, I photographed the signs today when the bakery wasn’t scheduled to be open, but the juxtaposition was still surprising.

In wartime, signs can be far more jarring. In 1982, I photographed this graffiti on a building in Guatemala during that country’s long-running insurgency. The right-wing graffiti on the left translates as “Death to the EGP (Guerrilla Army of the Poor) and the CUC (Committee for Peasant Unity).”

The graffiti on the right warns villagers: “Not a bread nor a tortilla for the guerrilla.”

This writing on a burned-out van proclaims: “Viva, the Army of Guatemala! Death to the Guerrilla Army of the Poor.”

Guerrillas too, of course, have traditionally written their own graffiti here and there. This warning was scrawled on a wall in San Agusta­n, El Salvador. Back in 1982 when I shot the photo, control of the town had been going back and forth between the government and the guerrillas. The insurgents’ message on this wall pockmarked by bullet holes is a threat directed at government informants: “Death to the ears.”

Wartime graffiti can at times be merely sarcastic. Because of deforestation brought on by trees being felled for heating and cooking, the Guatemalan government three decades ago restricted cutting trees in the wild.

However, guerrillas back then often toppled trees across rural roadways to block traffic. The trees, of course, had to be cut up to reopen the roads, and that prompted this graffiti which, judging from its red-white-and-blue colors, was painted by a member of the far-right National Liberation Movement (MLN).

The MLN graffiti sneers, “Thanks for the firewood, guerrillas, mules and sons of the whore.”

Even when signs are meant to be merely humorous reality can sometimes intervene. While in Paris in 1985, I saw a maid trudging wearily down the street with food for dinner. Immediately, I was struck by her incongruous juxtaposition with a billboard she was passing. It showed a laughing, topless woman about her age joking, “My shirt for a beer.”

Equally surprising was this scene I came upon a week ago at the entrance to Tilden Regional Parks Botanic Garden in Berkeley. Was this a guard cat or was the cat staying behind the sign so it wouldn’t be disturbed by dogs? I don’t know the answer, but I’m looking for a sign.