Bring out the theme of the story and the message O. Henry wanted to pass on in "One Thousand Dollars."
At the end of O. Henry's story, the lawyers are puzzled at the sound of Gillian's laughter as he leaves. He has lied and told them that he lost the one thousand dollars so that Miss Hayden will receive his inheritance. Against their opinion of him, Gillian has not been materialistic all his life although he has squandered his uncle's allowance to him. The message of this story, then, may well be that one's behavior is not always indicative of one's character because in the character of Gillian, the magnificence of love surmounts materialism. This idea is, then, the theme.
Young Gillian is a rather jaded young man who has lived in luxury thanks to his rich uncle; so, he has never really appreciated the value of a dollar. After his uncle dies, Gillian is given the neat sum of $1,000 and told by the lawyer that he must spend it and account for it in writing, as well.
So, after talking to Old Bryon at the men's club, Gillian goes to a stage actress's dressing room and offers her a diamond necklace for which the materialistic young woman is eager, but totally disinterested in Gillian. After asking people on the street whom he unfortunately finds less than ethical, Gillian rides to his uncle's mansion. When he learns that sweet Miss Hayden who has worked for his uncle, was only left a watch and ten dollars, Gillian places the money in an envelope, leaving it for her.
Later, the lawyers explain that there was a codicil to the will in which the uncle wanted to test Gillian to learn if he deserved his reward. Because he has given his money to Miss Hayden, Gillian now can receive $50,000. But, with O. Henry's typical ironic twist, Gillian proves his mettle as he ensures that Miss Hayden receives the money. He laughs as he departs because his heart is joyful from his gift of love, the truly valuable commodity.