Chinese Medicine incorporates Taoist thought including the concept of yin and yang which is so eloquently expressed by the traditional yin yang symbol. The symbol divides a circle which represents Tao or life into two tear dropped shapes, one black and the other white, which represents a divide of the unity of life into two equal but opposing energies - yin (black) and yang (white). Typically the black tear drop sinks to the bottom as it represents yin or the female element which is considered heavier as it is nourishing, moistening and cooling whilst the yang represented by white is floats to the top because it refers to the masculine element with it's qualities of lightness, activity and heat.
Within each tear drop shaped section is a dot of the opposite colour ie within the white tear drop there is a black dot and within the black tear drop there is a white dot. This symbolizes the concept that yin and yang do not exist as isolated energies - within yin there is yang (black dot in the white tear shape) and yang within yin (white dot within the black tear shape).
The two tear drop shapes imply some movement (from the larger area to the smaller pointier area on onwards) which is difficult to see in the traditional stylized version but easier to see in this coloured version. There is continuous flow between the state of yin and the state of yang as the Tao acknowledges that everything is always in a state of flux and a continual state of rebalancing . When things are in balance the flux between these two states is small as represented by being close to the centre. When things are out of balance the fluctuations are more exaggerated as indicated by the movement on the outer edge.
To sum it up the yin yang symbol speaks volumes in its simplicity, describing the dynamic flow of energy between yin and yang, their state of interdependance and harmony.