Why 108 bows? The 108 prostrations represent our basic mental sufferings. These sufferings arise through the meeting of the six sense organs. The eyes, ears, nose, tongue, body and mind and the six sense objects; namely corresponding color, sound, smell, taste, touch and concept.
It is the combination of these organs and sense objects that result in reactions of likes, dislikes or neutral feelings which in turn lead to joy, sorrow or indifference. Take these 6 combinations of sense organs and sense objects and multiply by the three reactions (likes, dislikes, neutral feeling, which turn to joy, sorrow or indifference) to equal 36; then multiply this by three for the past, present and future, giving us 108.
Doing 108 bows helps to sublimate and purify. By completely concentrating body and mind in unison, we rid ourselves of the scattering of energy that sensations and reactions cause us. Our basic nature is pure, infinite and capable of anything, but we keep losing our basic nature through our reactions to these sensory processes. We become incapacitated rather than infinitly capable, and we continue on the cycle of birth and death. But we can break the cycle of 108 sufferings by contantly repeating 108 prostrations, because it is then that the body and mind are pure and integrated as one. Such determination to return to our basic nature will eventually lead us to attain enlightment.
Read the 108 prostrations.