Ther knight is recognized for being helpful to the ones in need even when he cannot be paid for his services.He claims he cannot marry the old woman ,not because of her age ,but because of the fact that she has not shown any signs of gentility.The Knight wants to explain he will not marry a woman without goodness in her heart neither with the intentions of performing good actions towards the ones in need.
I'm pretty sure it is Theme. Theme is the central topic of the text. passage, story, or anything else. So it may possibly also be the same for the underlying meaning and universal truth...but again, I am not sure.
