Fig. 1.

Picture of the Yellow Thearch (“the yellow emperor”) with a citation from the book Huangdi Neijing [67]. On the right, a typical Chinese watchtower from Han Dynasty, Henan Province, first—second century AD (Art Gallery of New South Wales). The emperor suffered from symptoms that correspond to the modern concept of the syndrome of fear of heights when he climbed onto a clear, cold observation platform. He found out that kneeling down reduces these symptoms, a behavior which was later confirmed in psychophysical experiments: symptoms of fear of heights were strongest during free upright stance, moderate when the subject kneeled, and absent when the subject lied when looking down [3]