The open-ended curve of the spiral gives a sensation of continuous motion -- of life, in fact. In The Curves of Life, Sir Theodore A. Cook (1867-1928), English author and editor, finds that the spiral or helix may lie at the core of life's first principle -- that of growth. The spiral is fundamental to the structure of plants, shells, and the human body; to the periodicity of atomic elements and to an animal's horns; to microscopic DNA (the...