"I do not know whether there be, as a rule, more vocal expression of the sentiment of love between a man and a woman, than there is between two thrushes. They whistle and call to each other, guided by instinct rather than by reason"

In this quote, the author is reflecting on the expression of love between a man and a woman. He questions whether there is a noticeable difference in the singing expression of love in between humans which of 2 thrushes, a kind of bird understood for their lovely tunes. The author suggests that the singing expressions of love in between humans and thrushes are comparable, as they are both directed by instinct rather than reason. This might imply that love is a natural and instinctual feeling, instead of something that is purposely expressed. The comparison to thrushes likewise highlights the simpleness and pureness of love, as it is not affected by societal norms or expectations.