Six occupies the extreme of Obstruction with yin softness; braving the utmost danger to advance is why it encounters obstruction. Rather than advancing, coming back to follow the fifth and seek the third gains the assistance of firm yang, and is thus vast.
The path of Obstruction is one of distress, blockage, exhaustion, and constraint; 'vast' means broad, ample, and generous. Coming back brings breadth and ease, so that the obstruction is alleviated.
At the extremity of Obstruction there lies a way out; Six at the Top, being yin and soft, cannot escape on its own, but gaining the aid of firm yang allows it to alleviate the obstruction. In a time of extreme obstruction, obtaining relief is already good fortune.
Without firm, yang, central correctness, how could one truly emerge from Obstruction? 'It is advantageous to see the great man': in the extreme of Obstruction, seeing a person of great virtue enables one to overcome the hardship.
'The great man' refers to the fifth line, an interpretation derived from their close Adjacency. The fifth is firm, yang, balanced, and upright, occupying the ruler's throne, thus being the great man.
Why is the achievement of overcoming Obstruction not mentioned at the fifth line, but Six at the Top finds it advantageous to see him?
The answer is: at the fifth line it is not mentioned because it dwells within the Kan danger without firm yang assistance, hence lacking the sense of being able to overcome Obstruction.
For Six at the Top, obstruction has reached its extreme, and meeting a person of great virtue allows the obstruction to be surmounted, which is why it is advantageous.
Each line derives its meaning differently, just as the aspiration of the initial nine in Difficulty at the Beginning is correct, yet in Six in the Second Place it is viewed as a marauder.
None of the other lines speak of good fortune; Six at the Top alone speaks of good fortune because, though all the lines possess correctness and their respective merits, none are able to emerge from Obstruction and thus do not warrant good fortune.
Only the top line, dwelling at the extreme of Obstruction and attaining breadth and relief, achieves good fortune.