He saw (daydreamed) the Ouroboros (the snake biting it’s own tail) as a symbol for the benzene-ring.
Kekule is regarded as one of the principal founders of modern organic chemistry, the chemistry of carbon-based compounds. In 1858 he showed that carbon can link with itself to form long chains. In 1865 he reported his discovery of the benzene ring as the basis for another major group of carbon molecules.
Today we must be very grateful for his daydream, nearly all worldwide important things are made of plastic, which is created after it. The archeologues of the future will excavate plastic chairs, plastic bottles and plastic bags, like those of nowadays find monumental Egytian pharao-heads or Chinese emperors from clay.