The waning and waxing of energy and matter are the movement and rest of things; rising and retiring by day and night are the movement and rest of the body. Everything, including the advance and retreat of the person, the arising and vanishing thoughts, the fortune and adversity of the world, the success and failure of tasks, is a matter of the alternating rise and fall of movement and rest.
If you observe their patterns of movement and rest. you can see the myriad changes of myriad events and the conditions of myriad beings. When you are mindful in times of rest, you are observant in times of movement. If you have self-mastery in times of rest, you can be decisive in times of movement. If you have stability in times of rest, actions will not lead to unfortunate results. Rest is the foundation of movement, movement is the potential of rest. When you do not lose the constant in movement and rest, your path will be illumined.
Reference: Quote from the Book of Balance and Harmony in The Taoist “I Ching” by Liu I-ming and Thomas Cleary