But the rise of the symbol is by no means bad--and by no means new.

Although there is some truth to the idea that a focus on symbols is correlated with illiteracy. Symbols, after all, stand for words and ideas. If you can't read words, the only way to comprehend an elaborate idea is to look at a visual representation of it. If the visual representation is good and clear--as warning signage invariably is--the idea should suggest itself on its own. In some cases, the idea-as-symbol takes on meaning beyond the original confines of the symbol.

Take early Christian symbology, one of the biggest sources of common symbols in the European tradition. The success of the Catholic Church at establishing theological dominance depended on the Church's ability to contain and marginalize heresy, especially heresy related to the doctrine of the Holy Trinity. But how do you communicate a subtle concept like "The Holy Spirit" to audiences who've never had an education beyond twelve hours a day pushing a plow for their feudal lords? The answer: express the holy spirit as a drawing of a bird, and put those drawings where people can see them: in common gathering places, repositories for knowledge. In other words, in the church--in the stained glass windows.

Think of stained glass windows as the airline diagrams of the Middle Ages.

Once the Holy Spirit was commonly thought of as a bird, the concept--already vaguely defined in the existing religious literature--started to take on new meanings, to "stretch its wings." The notion of winged angels began to arise, human-looking figures who had taken on the aspects of birds. The whole notion of heaven as being an "upward" place, a kingdom in the clouds, was in no small way determined by the use of the bird symbol. And contemporary shorthand symbols for ideas--notably, the "dove of peace"--are unthinkable without the initial religious bird imagery. A vague concept must be communicated to a lay audience. It must be translated into a symbol. And suddenly the symbol takes on new meaning--changed by its new language, the language of symbols.

Maybe it's a stretch to think that one day cultural historians will study our fire extinguisher signs as assiduously as they study alchemical manuscripts and other rich veins of classical symbols. And maybe it's a stretch to think that the warning signage of today will suggest infinite, subtle meanings to the historians of tomorrow--that it may found new religions, new philosophies, new ways of looking at mankind. One thing isn't a stretch, though: we're living in the age of the symbol. And we have been for a very long time.