All 11 Uses of

motive
in
Persuasion, by Jane Austen

She could do justice to the superiority of Lady Russell's motives in this, over those of her father and Elizabeth; she could honour all the better feelings of her calmness; but the general air of oblivion among them was highly important from whatever it sprung; and in the event of Admiral Croft's really taking Kellynch Hall, she rejoiced anew over the conviction which had always been most grateful to her, of the past being known to those three only among her connexions, by whom no syllable, she believed, would ever be whispered, and in the trust that among his, the brother only with whom he had been residing, had received any information of their short-lived engagement.†
Chpt 4

motives = reasons for doing something

It was now some years since Anne had begun to learn that she and her excellent friend could sometimes think differently; and it did not surprise her, therefore, that Lady Russell should see nothing suspicious or inconsistent, nothing to require more motives than appeared, in Mr Elliot's great desire of a reconciliation.†
Chpt 16 *

How glad they had been to hear papa invite him to stay dinner, how sorry when he said it was quite out of his power, and how glad again when he had promised in reply to papa and mamma's farther pressing invitations to come and dine with them on the morrow—actually on the morrow; and he had promised it in so pleasant a manner, as if he felt all the motive of their attention just as he ought.†
Chpt 7

He saw you then at Lyme, and liked you so well as to be exceedingly pleased to meet with you again in Camden Place, as Miss Anne Elliot, and from that moment, I have no doubt, had a double motive in his visits there.†
Chpt 21

Mr Elliot came back accordingly; and on application was forgiven, as you know, and re-admitted into the family; and there it was his constant object, and his only object (till your arrival added another motive), to watch Sir Walter and Mrs Clay.†
Chpt 21

My spirits rallied with the morning, and I felt that I had still a motive for remaining here.†
Chpt 23

Definitions:

(1) (motive as in: What is her motive?)
a reason for doing something
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

Less commonly, motive can refer to something that causes motion in an inanimate object. Even less commonly, it can refer to a distinctive feature in music, art, or literature.