Answer:
The author in "On his blindness" refers to his blindness.
Explanation:
Jorge Luis Borges, the author of this poem, suffered from blindness and that is what he reflects in this poem.
What he means when he says "it breaks things down into a single thing, colorless, formless" is how he sees things because of blindness, as formless and colorless things.
This poem has a melancholic tone. The blindness that came to Borges in 1955 meant a great change for him, since he was a lover and fond of reading.
