physically aware—represent no more than a single step in the ladder which has no bottom nor no top. You can not conceive an end in either direction. There is no such thing. Nor—as Father says—can you declare anything to be small or large considered by itself alone. This then is Space as we conceive it to be. Illimitable, unending—infinite Space."
The conception momentarily seemed wholly beyond my grasp. What I would have answered when for a moment Dr. Gryce and Brett paused I do not know, for from the house the approaching voices of Martt and Frannie reached us.
"You'll fall, I tell you! Frannie, give me that!"
"I won't."
"You'll trip over the wires and you'll fall and smash it!"
"I won't."
The sound of a crash. And Martt's voice, "There, I told you!"
They were upon us, wheeling the tray laden with breakfast; Martt, flushed, laughing. "Oh, hello, Frank—they didn't switch you wrong, did they? Frannie broke the heater coils—if the breakfast gets cold, don't blame me."
And Frannie, also flushed and laughing and a trifle rueful over the mishap. Dressed in a blue blouse and widely flaring, knee-length trousers, with her golden hair tossing on her shoulders. The picture of a little housewife, of early morning informality. I thought I had never seen her so beautiful.
III
"That, Frank, is our conception of the infinity of Space."
With breakfast finished Brett had resumed the discussion. We were all seated in the arbor. Martt and Frannie momentarily were quiet, seemingly keenly interested in the impression upon me which they anticipated would come from their father's disclosures.
Dr. Gryce said, "The idea of Time unending is indissolubly bound with the concept of infinite Space. You will realize, Frank, for some centuries it has been understood that Time and Space are inextricably blended. We think instinctively of Space as a tangible entity—of length, breadth and thickness. And of Time, as intangible. Such really is not the case. Space has three dimensions—but Time also has a dimension."
"Length," Martt put in. "It sounds like a play on words, but"
"It isn't," Frannie finished for him. "I can't imagine anything clearer than that Time has length."
Dr. Gryce ignored them. "You must understand also that Time as we conceive it can not exist except as the measurement of a length between two events. And what is an event? It presupposes the existence of Matter, does it not? Matter thus is introduced into the universe. It also can not be independent of Time and Space. So long as anything material exists, there must be Space for it to exist in; and Time to mark the passing of its existence.
"Of our universe, then, we now have Matter, Time and Space. There is a fourth—shall I say, element? It also is interdependent with each of the other three. It is Motion. You know, of course, that there can be no such thing as absolute Motion."
"Or absolute Time," Frannie put in.
"That we will discuss later," Dr. Gryce said quickly, "since it is more intricate of conception. Absolute Motion is impossible and non-existent. We can say a thing moves fast or slowly, only in relation to the movement of something else. One word more. I want you to realize, Frank, how wholly dependent each of these factors is upon the other. Matter,
