The whole weasel question

Consider the case of a mathematician, in this case
My oldest brother, who is (a) halved by an illness,
(b) stilled completely by it, and (c) reduced to ash.
Trust me, he would be the first to note that finally
He finished his travels at 0.00416666667 of what
He weighed for a long time. I bet then he’d spend
Weeks poking into what else weighed exactly that.
I’d get a terse note with a list in his meticulous ink:
The cardinal on average weighs 0.992 of a pound,
And the long-tailed weasel weighs exactly a pound.
A letter like that is exactly like a zen koan, I think.
It’s as much a door as a statement. Let us consider
That we have all just now received this terse letter.
It sits there grinning on the table next to the coffee.
I don’t know about you, but I am going to dive into
The whole weasel question. We have so little time,
And there’s so much to be discovered. I want to be
Able to be conversant about this the next time I see
My brother. He’ll want to know. He’ll have missed
A lot of time that could have been devoted to these
Things, and someone has to carry the ball, whether
It’s weasels or cardinals or cancer. How mortifying
It will be if he asks me about something, and I have
To say I didn’t pay attention, man, and he will stare
At me with that laser stare and not even have to say,
And what was it you did instead of paying attention?