"People have used all sorts of artificial devices probably from the beginnings of human history to help them compensate for the loss of a limb. Thus in very ancient times, the first and simplest prosthesis may have been a forked tree that was used as a crutch to help someone walk whose leg may have been badly damaged or lost in an accident or to a disease. What began as a modified crutch with a wooden or leather cup and progressed through many metamorphoses has now developed into a highly sophisticated prosthetic limb made of space-age materials."