What is the word of Du Fu's poetic eye combined with the whole poem analysis when climbing the mountain?

Poetry Eye is the first two pairs of "sad" couplets describing autumn scenery, and it was not until the Neck Couplet that it was named after the word "autumn". "Alone on the stage" shows that the poet is overlooking from a height, which closely connects his eyes with his heart. Frequent visitor points out the poet's wandering life. "Hundred years" is a metaphor for limited life, especially the twilight. The word "sad autumn" is written very painfully. Autumn is not necessarily sad, but when the poet witnessed the desolate and magnificent autumn scenery, he couldn't help thinking of his own exile, the old, the weak and the sick, so he gave birth to infinite sadness. The poet summed up the feelings of a long-time guest who is most likely to be sad and sick and loves to go on stage alone into a pair of couplets that are "bold and broad, loyal and loud", which makes people deeply feel his heavy emotional pulse. The "Wan Li" and "Centennial" of this couplet also echo the "boundless" and "endless" of the previous couplet: the poet's travel worries and loneliness, like fallen leaves and rivers, are pushed and driven away endlessly, and his feelings and scenery are integrated. At this point, the poem has given the general meaning of missing a stranger, added the content of loneliness after a long separation, added the feeling of sadness and pain in autumn, added the sigh of people who have left their homes in Wan Li and are in their twilight years, and is more poetic.