Sirius Judges, Seriously

Sirius sneers upon me and says:
"Here you are that shines, and I
compare the moon- what is your design,
that which you aim to do?"

"For if I am brightest but in eye burns
only you- what heart am I left
by sky to move?"

I detract with grin and say:
"Loyal hound, all men have sought
to be your sight- all men live by you
and I cannot compare by night."

and the star says: "I am still the light-
yes, I am still the light."