Distinction is made between two kinds of rulers :
The constituting ruler of the hexagram is that line which gives the hexagram its characteristic meaning, regardless of whether or not the line indicates nobility and goodness of character.
The weak top line in hexagram 43, Kuai, BREAK-THROUGH (RESOLUTENESS) is an example, for the idea that this line is resolutely to be cast out is the constituting factor in the hexagram.
Governing rulers are always of good character and become rulers by virtue of their position and the meaning of the time. Usually they are in the fifth place, but occasionally lines in other places may be governing rulers.
When the constituting ruler is at the same time the governing ruler, the line is certain to be good and to be in the place appropriate to the time. When it is not the governing ruler as well, it is a sure sign that its character and place do not accord with the demands of the time.
The ruler of the hexagram can always be determined from the Commentary on the Decision. When the constituting ruler and the governing ruler are identical, the hexagram has one ruler; otherwise it has two. Often there are two lines constituting the meaning of the hexagram, as for instance the two advancing weak lines in hexagram 33, Tun, RETREAT; these are both rulers because they are pushing back the four strong lines. If the hexagram is produced by the interaction of the images of the primary trigrams, the two lines respectively characterizing the trigrams are the rulers.