What is the book of synonyms called

"the trouble is," sighed the doctor, grasping her meaning intuitively, "that youth is given up to illusions. it seems to be a provision of nature; a decoy to secure mothers for the race. and nature takes no account of moral consequences, of arbitrary conditions which we create, and which we feel obliged to maintain at any cost." what larger idea is the doctor referring to when he says that nature takes no account of moral consequences? impulses often overrule a person’s sense of good and bad. nature forces women into motherhood. young people are prone to having delusions. morals play no role when we choose who we love.

Which type of story uses animals as characters in order to illustrate a general truth about human nature?

May someone me answer these questions