When moving in T'ai Chi Chih® all parts of the body should move together. Everything should be connected. Proper alignment is of the utmost importance. Without this proper alignment the Chi will not flow properly. To keep your alignment your body must move in harmony. When you move one muscle this will effect all the others. Relax the every part of your body. Tension is your enemy. Tension will block the flow of Chi.
When the flow of Chi is blocked the parts become disconnected. You must release all tension. Without tension the Chi will flow freely and connect all the parts of your body and mind. This allow you to flow with softness and continuity. T'ai Chi Ch'uan Ching attributed to Chang San-feng describes this principle.