Natubiki no ito 夏引の糸, which I have translated here as ‘Spun in summer/A silken thread’ was thread drawn from the cocoons of the harugo 春蚕 silkworm, which was ready for harvesting at the beginning of summer. Sanekata’s reasons for mentioning it are twofold: first, for the connotations of silk cloth and, by association, the light summer clothes the lady will have just changed into; and second, so he can engage in wordplay with the ito element, making it part of ito ni Fa arazu ‘not terribly (unwell)’ . The lady in her reply reuses natubiki no ito, but in this case she refers to the seeming endless thread of silk drawn from a cocoon as a metaphor for the extent of her concern for Sanekata.