“Is that the name of it?” said Rollo.
“Yes,” said Mary. “When you tie a little stone to a string, and hold the upper end of the string still, and let the stone swing back and forth, it makes oscillations.”
“I mean to try it,” said Rollo.
“Yes,” said Mary; “and I will help you by and by, after I have studied my philosophy lesson.”
“Your philosophy lesson?” asked Rollo. “Have you got a philosophy lesson to get?”
“Yes,” said Mary, “in that great book.”
So Rollo took up Mary’s book, which she had laid down upon the platform near Rollo’s apparatus. He found that the title of it was “Intellectual Philosophy.”
“Intellectual Philosophy?” said Rollo; “and what sort of philosophy is intellectual philosophy?”
“It is the philosophy of the mind,” replied Mary. “It explains to us about the thoughts and feelings of our minds.”