Symbols are syntheses of concepts, they have direct comprehension, and enhance the expressive possibilities of things. Here are some significant symbols in human history. Lightning, the terror of primitive man. The wheel, which alludes to the movement of the sun and recalls the wheel of a farm cart. The musical note: cultured man accompanies his words and songs with music. The triangle, perfection, which, combined with the circle, symbolizes universal harmony, time, and space.