It is but a poor, valueless thing, but it will bring you in your five francs, at any rate.

Go! I desire you.' "'But I cannot,' said the boy, hesitating; some dim sense of honour flitting through his misty morals.
"'Yes, you must!' she continued, urging him with her hand to the door.
'Run! if it brings in more than five francs, you shall return the surplus to me.' "Thus tempted by her urgency, and, I suppose, reasoning with himself to the effect that he might as well have the money, and then see whether he thought it right to act as a spy upon her or not--the one action did not pledge him to the other, nor yet did she make any conditions with her gift--Pierre went off with her ring; and, after repaying himself his five francs, he was enabled to bring Virginie back two more, so well had he managed his affairs.

But, although the whole transaction did not leave him bound, in any way, to discover or forward Virginie's wishes, it did leave him pledged, according to his code, to act according to her advantage, and he considered himself the judge of the best course to be pursued to this end.

And, moreover, this little kindness attached him to her personally.

He began to think how pleasant it would be to have so kind and generous a person for a relation; how easily his troubles might be borne if he had always such a ready helper at hand; how much he should like to make her like him, and come to him for the protection of his masculine power! First of all his duties, as her self-appointed squire, came the necessity of finding out who her strange new acquaintance was.
Thus, you see, he arrived at the same end, via supposed duty, that he was previously pledged to via interest.