All 4 Uses of

oblige
in
The Adventures of Tom Sawyer

If he had been a great and wise philosopher, like the writer of this book, he would now have comprehended that Work consists of whatever a body is OBLIGED to do, and that Play consists of whatever a body is not obliged to do.†
Chpt 2 *

If he had been a great and wise philosopher, like the writer of this book, he would now have comprehended that Work consists of whatever a body is OBLIGED to do, and that Play consists of whatever a body is not obliged to do.†
Chpt 2

Yet he felt obliged to speak up and say: "Answer the gentleman, Thomas—don't be afraid."†
Chpt 4

There is no school in all our land where the young ladies do not feel obliged to close their compositions with a sermon; and you will find that the sermon of the most frivolous and the least religious girl in the school is always the longest and the most relentlessly pious.†
Chpt 21

Definitions:

(1) (oblige as in: I am obliged by law.)
require (obligate) to do something
(2) (oblige as in: I obliged her every request.)
grant a favor to someone
(3) (obliged as in: I'm much obliged for your kindness)
grateful or indebted
(4) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

Much more rarely, in classic literature you may see oblige as a synonym for ask as when Jules Verne wrote "I obliged the Professor to move his lamp over the walls of the gallery," in Journey to the Center of the Earth.