In the case of the ball thrown upward, at the start, at the finish, or at any intermediate point of either its ascent or descent, the sum of the two types of energy is the same. It may be all kinetic, all potential, or partly both. In any case, the sum of the two continually varying energies is constant. Just as a man may have a hundred gold dollars, now in his hand, now in his pocket, now part in his hand and the rest in his pocket; changing a dollar at a time from hand to pocket or vice versa, the amount of money in his possession remains constant, viz., one hundred dollars.