Along with symbolic meaning, the suggestion of Barbara Ansley that she and Jenny Slade "...leave the young things to their knitting" contains much irony. For, the knitting to which Mrs. Slade and Mrs. Ansley are left is the knitting together of an old memory and the hidden truth contained within it. Certainly, the intensity of the revelation that Mrs. Ansley makes to her old friend contains more intensity to it than any rendezvous of the young woman on this night.
As the two older women reflect upon their lives, Mrs. Spade eventually reveals that she forged a letter from her then fiance, Delphin Slade, to Grace Ansley in the hopes that Grace would come out into the night air and contract Roman fever. In this way, Grace would be removed as an impediment to her engagement to the wealthy Delphin. However, Mrs. Spade's pride in her subterfuge unravels as Mrs. Ansley continues to "knit" together the events of that evening so long ago. For, after Mrs. Ansley rises, remarking on the cold, she says, "I'm sorry for you."
"I don't know why you should be sorry for me," she [Mrs. Slade] muttered.
Mrs. Ansley stood looking away from her toward the dusky secret mass of the Colsseum. "Well--because I didn't have to wait that night."
Mrs. Ansley had responded to the letter purportedly written by Delphin; he arrived to meet her then at the Coliseum. Still, Mrs. Spade counters that she had Delphin all these past years while Mrs. Ansley only had a letter he did not write. But, Mrs. Ansley refutes her assertion, "I had Barbara." With this statement, the carefully knitted plot of Mrs. Slade, formed so long ago, comes unraveled.
This quote comes from the short story "Roman Fever" by Edith Wharton, and so I have moved this question to the appropriate group. Barbra utters this quote at the beginning of the story, and within the hearing of the two old women that are referred to ironically as the "young things." Symbolically, the quote emphasises the difference in age and generation between the two main characters of the story and their daughters. Barbra qualifies that she refers to knitting "figuratively," saying that "we haven't left our poor parents much else to do." Thus, symbolically, the "knitting" refers to the time of life that Mrs. Ansley and Mrs. Slade have reached. They have left behind the time of going out and courting and seeking a husband, leaving their daughters to engage in such activities, and are now left with lots of time on their hands. Note what Mrs. Ansley says:
"The new system has certainly given us a good deal of time to kill..."
Thus the two principal characters are left with each other to look at the view, knit and talk, activities befitting their stage in life.
Kntting is something that normal housewives usaully do, and this gives us a sense that the two middle-aged lady are sterotyped widows who has a dull and passive life.
Ironically, till the end of the story, we knew that the 2 ladies actually had a passionate and vigourous love life and compeition that would even lead to murder.
This may also be interpreted as 'people are not what them seem.
'Let's leave the young things to their knitting'
'Well I mean figuratively'
After all, we hacen't left our poor paretns much else to do'
These impression of their mothers by the daughters suggested how little and superficial they know of their parents and the distance between them.