The grandmother said, 'How did you come to know to seek me?'

曉得, to have come to know, with 得 as the unstressed de. She has been forgotten for eighteen years, and her first response is not joy but bewilderment that anybody knew where to look.

Xuanzang said, 'It was my mother who sent me to seek you, grandmother.'

著 here is zhuó, to set somebody to a task — a third reading for a character that has already been zhe and zháo in this chapter. My mother sent me: the answer is that somebody remembered.

'My mother has a letter here, and an incense-ring besides.'

一隻, one of them, singular. A letter and a ring — and for a woman who cannot see, the ring is the part that does the work.

The grandmother took the letter and the ring, and crying aloud wept:

放聲, letting the voice out, is the exact opposite of the 含淚, tears held in, that his mother managed at the riverside. Nobody here has appearances to keep up.

'My son went for fame and office and came to this; I only thought he had turned his back on duty and forgotten kindness — who would have known he had been murdered?'

Here is the wound underneath the blindness. 我只道, I always assumed: she has spent eighteen years believing her son abandoned her. 背義忘恩, turning your back on duty and forgetting what you owe, is a serious charge, and she has been quietly making it all this time. 為功名 takes 為 as wèi, for the sake of; 那知 takes 那 as the question word nǎ, in the sense of how was I to know.

'Yet I am glad that Heaven took pity and did not cut off my son's line —'

不絕, did not cut off, and 後 here means descendants, what comes after. In a world where the worst thing that can befall a family is simply to stop, the grandson standing in front of her is not consolation. He is repair.

'today there is even a grandson come to seek me.'

孫子, grandson, with 子 unstressed as zi; 還有, there is even, takes 還 as hái. The feeling sits in that 還: after all of it, there is still this.

Xuanzang asked, 'Grandmother, how is it your eyes are both gone blind?'

都 is dōu, both of them. He asks about her eyes, which is the first thing anybody has asked her in years.

The grandmother said, 'Out of longing for your father, day after day I gazed for him and he did not come, and so I wept till both my eyes went dark.'

思量, to think a thing over and over, takes 量 as liáng. 懸望 is hanging on the lookout, waiting with your hopes suspended. Then the cause, stated as flatly as a diagnosis: 哭得兩眼都昏了, wept until both eyes went dark, with 得 as de and 都 as dōu. She did not lose her sight to age. She cried herself blind waiting for a man who was already at the bottom of a river.