 Five Phase theory is also applied in diagnosis and therapy.Correspondences between the body and the universe have historically not only been seen in terms of the Five Elements, but also of the "Great Numbers" () For example, the number of acu-points has at times been seen to be 365, corresponding with the number of days in a year; and the number of main meridians–12–has been seen as corresponding with the number of rivers flowing through the ancient Chinese empire.TCM "holds that the body's vital energy ("chi" or "qi") circulates through channels, called "meridians", that have branches connected to bodily organs and functions."