Nine in the fourth place is the best practical reading in Great Power. The obstacle opens, the horns stay clear, and the regret attached to the situation disappears. A querent drawing this has usually been holding back after an earlier overreach, and the line releases them to act, with the qualification that the good fortune is attached to firm correctness rather than to the force itself.
The position is why it works. A strong stroke stands at the foot of the thunder trigram Zhen with three more firm lines beneath it, so the whole weight of the lower half of the figure is behind the movement, and by the ordinary rule the placement is incorrect, a strong line in an even seat. The classic repeatedly finds that a line without formal entitlement handles power better, because it has to find a way through instead of assuming one is owed.
When the line changes, the upper trigram Zhen becomes Kun and the figure becomes Peace, King Wen 11, heaven below and earth above, the two moving toward one another so that everything passes freely. That is an unusually generous destination and it fits the line exactly. An obstruction removed by strength that did not entangle itself leaves an open channel behind it, and what follows is not another exertion but a stretch in which things simply go through.