Today, we learn to write. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

We learned to write not long before 3100 BC. The wheel was then only a few hundred years old. Copper was just coming into use. The technologies that would set the course of civilization were all being created at roughly the same time.

Surely writing was among the strangest of these. It was the result of a great abstraction. First we turned our thoughts into spoken words. Then we invented a second means for handling our ideas. We froze words into a lasting visual experience.

And yet this sequence may miss the point. That's because writing flows as much from picture-painting as it does from speech. And picture-painting had already been around for 30,000 years when we took up writing. Writing breaks away from painting, just as it breaks away from speech. Both separate their subjects from actual events.

For example, a picture of men hunting a lion puts the actual event into an eternal present tense. Suppose you want to say different things about the event: They are hunting the lion. I would like to hunt a lion. Four men once hunted a lion. Go out and get me a lion. Stay downwind when you hunt lions. The picture doesn't let you manipulate the act. Both speech and writing abstract the elements of an event or of a picture. They let you move the elements around, like pieces of a puzzle.

The ancient Sumerian people began using a pictographic writing in 3100 BC. They probably didn't invent it. We're finding that various North African people wrote just before the Sumerians did. Egyptian pictographs show up about a hundred years earlier. The Mande people of the western Sahara also used streamlined pictographs that seem to date back at least as far as that. Other North African systems of picture writing are known. The first writing seems to have been a match in the tinder box of the mind. Whoever first thought of it, it seized the imagination. Writing suddenly popped up in many places.

I have my own reason for believing the African claims over the Sumerian ones. That belief rises out of my knowledge of invention. The Africans used writing to honor the dead and to speak of the inner self. The Sumerians used it to record the affairs of business and management. That use lay far away from the intent of either pictures or poetry.

Nothing as close to the human heart as writing is could have been created only to record commerce. The great inventions all come out of some far more personal corner of our inner being.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

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A great deal is written about writing (start with your encyclopedias). The African slant is given by two articles in Blacks in Science, Ancient and Modern (I. Van Sertima, ed.). New Brunswick: Transaction Books, 1983.

Johnson, W.R., The Ancient Akan Script: A Review of Sankofa. By Niangoran-Bouah, pp. 197-207.

Winters, C-A., The Ancient Manding Script. pp. 208-214.