Nine at the beginning answers a querent who is reconsidering a commitment: an allegiance, a project, a line of work, a person whose lead they have been taking. The reading is favourable to the change and unusually specific about how to make it. Alter the aim, hold to what is correct while doing so, and then seek company outside the existing circle rather than reassembling the same group around a new plan.
The second half is the part querents most often skip. Having changed direction, the natural move is to bring along whoever is already close, because those relationships are established and cost nothing to maintain. The line treats that as the way the change fails. Merit is promised for going beyond the gate, which in a practical reading means new colleagues, unfamiliar rooms, people with no stake in the previous arrangement and no reason to defend it.
The condition on the good fortune is firmness, and it applies to the new direction rather than the old one. A querent who changes objective and then keeps revisiting the decision has not really changed it. What the line describes is a single clean turn followed by steady pursuit, and it is worth noting that this is the only position in the hexagram where the querent is the one choosing what to follow rather than being caught in an attachment already formed.