We saw in the previous chapter that cyclic coordinates lead to their conjugate momenta being constants of motion. We also saw that when the Lagrangian does not depend explicitly on time, the total energy of the system is conserved (or more precisely, the Jacobi integral is conserved). These conservation laws can be put in a more general form that states that for each symmetry in the action, there is a corresponding conserved quantity. This is called Noether’s theorem.