Uncle Tim stared a moment, and then began to fill up his pipe, whistling the tune of High Betty Martin, while the Doctor went on:
“The earth, I say, may exist, although Bishop Berkeley has proved beyond all possible gainsaying or denial, that it does not exist. The case is clear; the only difficulty is, to know whether we shall believe it or not.”
“And how,” asked Uncle Tim, “is all this to be found out?”
“By digging down to the first principles,” answered the Doctor.
“Ay,” interrupted Malachi, “there is nothing equal to the spade and pickaxe.”
“That is true,” said my grandfather, going on in Malachi’s way, “ ’tis by digging for the foundation that we shall find out whether the world exists or not; for, if we dig to the bottom of the earth and find a foundation—why then we are sure of it. But if we find no foundation, it is clear that the world stands upon nothing, or, in other words, that it does not stand at all; therefore, it stands to reason—”
“I beg your pardon,” interrupted the Doctor, “but you totally mistake me; I use the word digging metaphorically, meaning the profoundest cogitation and research into the nature of things. That is the way in which we may ascertain whether things are or whether they are not.”
“But if a man can’t believe his eyes,” said Uncle Tim, “what signifies talking about it?”
“Our eyes,” said the Doctor, “are nothing at all but the inlets of sensation, and when we see a thing, all we are aware of is, that we have a sensation of it; we are not sure that the thing exists. We are sure of nothing that we see with our eyes.”
“Not without spectacles,” said Aunt Judy.