The old maid was his housekeeper and did all the cooking and sewing.

A happier couple never lived.
Celibates both, they were bound together by an equal hatred of marriage.
The sister abhorred all men, the brother looked upon all women with suspicion; but they adored each other, each considering the other an exception to the general perversity of the sex.
In speaking of him she always said: "Monsieur Planus, my brother!"-- and he, with the same affectionate solemnity, interspersed all his sentences with "Mademoiselle Planus, my sister!" To those two retiring and innocent creatures, Paris, of which they knew nothing, although they visited it every day, was a den of monsters of two varieties, bent upon doing one another the utmost possible injury; and whenever, amid the gossip of the quarter, a conjugal drama came to their ears, each of them, beset by his or her own idea, blamed a different culprit.
"It is the husband's fault," would be the verdict of "Mademoiselle Planus, my sister." "It is the wife's fault," "Monsieur Planus, my brother," would reply.
"Oh! the men--" "Oh! the women--" That was their one never-failing subject of discussion in those rare hours of idleness which old Sigismond set aside in his busy day, which was as carefully ruled off as his account-books.

For some time past the discussions between the brother and sister had been marked by extraordinary animation.

They were deeply interested in what was taking place at the factory.

The sister was full of pity for Madame Fromont and considered her husband's conduct altogether outrageous; as for Sigismond, he could find no words bitter enough for the unknown trollop who sent bills for six-thousand-franc shawls to be paid from his cashbox.