主题：这段英文描写说明了一个什么道理呢？

你能从以下这段英文描写的事情当中想到中国的一句古训吗？你知道这句古训英文怎么说吗？

It was drizzling in a windy autumn day. The bus I took was sparsely occupied, offering chances to choose a seat. When it came to a stop, a middle-aged woman got on with an umbrella. She didn’t close it as she stepped on the footboard, drawing attention of those inside the bus. It was a three-fold umbrella, as fashionable as its owner, a good-looking woman in neat dress.
She approached a seat and frowned after a glance, looking disgusted and murmuring a few words. I cast eyes in that direction and found the seat moistened by a previous occupant unawares.
She turned around, chose a double seat and sat down comfortably. When she did so, as I noticed, she casually or unwittingly put her wet umbrella on the seat beside hers.
It was still drizzling when the bus went along. The passengers sat nonchalantly, paying no attention to others. But I was restless, pestered by the thought of that wet umbrella and the seat it occupied. How naturally she did so! Why didn’t she frown at her own deed as she had at somebody else’s?