“Now folds the lily all her sweetness up, / And slips into the bosom of the lake: / So fold thyself, my dearest, thou, and slip / Into my bosom and be lost in me.”

Tennyson sets a sleeping flower against the speaker's own sleeplessness, and then asks the beloved to fold herself up and disappear into him. It is an image of love as a place where someone is kept rather than encountered, which is why it reads as both tender and unsettling.