indispensability

In thinly-peopled spots, I have known brick-layers on tramp, coming up with bricklayers at work, to be so sensible of the indispensability of lookers-on, that they themselves have sat up in that capacity, and have been unable to subside into the acceptance of a proffered share in the job, for two or three days together.

Beetle: Yes, I am certain I can be helpful. Indispensable!

Monkey: In what way?

[Beetle displays his ability with bow and arrow, firing multiple arrows on the same spot]

[…]

Beetle: Just tell me of our quest, and I will immediately demonstrate my numerous indispensabilities.