The act was out of politeness, because he needed something.
Now one of the cardinal rules of politeness is to avoid burdening a stranger with the weight of ones own woes.
Dean took a seat and joined her, part politeness, part to guard the remaining slice.
The vicomte was a nice-looking young man with soft features and polished manners, who evidently considered himself a celebrity but out of politeness modestly placed himself at the disposal of the circle in which he found himself.
In the middle of one of the longest sentences, he stopped the rotary motion of the snuffbox, raised his head, and with inimical politeness lurking in the corners of his thin lips interrupted Weyrother, wishing to say something.