"Do as beseems an honored cavalier"?

Which one persistent question-torture,—plied

Day by day, week by week, and month by month,

Morn, noon and night,—fatigued away a mind

Grown imbecile by darkness, solitude,

And one vivacious memory gnawing there

As when a corpse is coffined with a snake:

—Fatigued Onofrio into what might seem

Admission that perchance his judgment groped

So blindly, feeling for an issue—aught