You know you mustn't hit a girl--" "I should think not, indeed," muttered Peter, indignantly.
"Not even if she's your own sister.

That's because girls are so much softer and weaker than we are; they have to be, you know," he added, "because if they weren't, it wouldn't be nice for the babies.

And that's why all the animals are so good to the mother animals.

They never fight them, you know." "I know," said Peter, interested; "two buck rabbits will fight all day if you let them, but they won't hurt a doe." "No; and quite wild beasts--lions and elephants--they're immensely gentle with the female beasts.

And we've got to be, too." "I see," said Peter.
"And their hearts are soft, too," the Doctor went on, "and things that we shouldn't think anything of hurt them dreadfully.