"Yes, that is why."

"And you think that you would lose your vision if you went among
people?"

"I know that I should."

"But how do you know?"

"I know because I have tried. You don't realize how hard I have to
work over a thing like this. I have carried it in my mind for a
year; I have lived for nothing else--I have literally had no other
interest in the world. Every sentence I have read to you has been
the product of work added to work--of one impulse piled upon
another--of thinking and criticizing and revising. Just the little
bit I have done has taken me a whole month, and I have hardly
stopped to eat; it's been my first thought in the morning and my
last at night. And when the mood of it comes to me, then I work in a
kind of frenzy that lasts for hours and even days; and if I give up
in the middle and fall back, then I have to do it all over again.
It's like toiling up a mountain-side."

"I see," whispered Corydon. "And then, do you expect to have no
human relationships as long as you live?"

Thyrsis pondered for a moment. "Did you ever read Mrs. Browning's
poem, 'A Musical Instrument'?" he asked.

"No," she answered.