The Hazer would be arriving at about the same time as Ulysses and the three of them could spend a pleasant evening. It was not too often that two goo… - Clifford D. Simak

There was no time, Hezekiah had said. No such thing as time in the terms of normal human thought. Time was bracketed and each of its brackets contained a single phase of a universe so vastly beyond human comprehension that it brought a man up short against the impossibility of envisioning it.
And time itself? Time was a never-ending medium that stretched into the future and the past — except there was no future and no past, but an infinite number of brackets, extending either way, each bracket enclosing its single phase of the Universe. Back on Man's original Earth, there had been speculation on travelling in time, of going back into yesterday or forward into tomorrow. And now he knew that you could not do it, that the same instant of time remained forever within each bracket, that Man's Earth had ridden the same bubble of the single instant from the time of its genesis and that it would die and come to nothing within that self-same instant. You could travel in time, of course, but there would be no yesterday and no tomorrow. But if you held a certain time sense you could break from one bracket to another, and when you did you would not find yesterday or tomorrow, but another world.

Jenkins tried to say goodbye, but he could not say goodbye. If he could only weep, he thought, but robots could not weep.

There isn’t any room,” said Joshua. “You travel back along the line of time and you don’t find the past, but another world, another bracket of consciousness. The earth would be the same, you see, or almost the same. Same trees, same rivers, same hills, but it wouldn’t be the world we know. Because it has lived a different life, it has developed differently. The second back of us is not the second back of us at all, but another second, a totally separate sector of time. We live in the same second all the time. We move along within the bracket of that second, that tiny bit of time that has been allotted to our particular world.” “The way we keep time was to blame,” said Ichabod. “It was the thing that kept us from thinking of it in the way it really was. For we thought all the time that we were passing through time when we really weren’t, when we never have. We’ve just been moving along with time. We said, there’s another second gone, there’s another minute and another hour and another day, when, as a matter of fact the second or the minute or the hour was never gone. It was the same one all the time. It had just moved along and we had moved with it.” Jenkins nodded. “I see. Like driftwood on the river. Chips moving with the river. And the scene changes along the river bank, but the water is the same.” “That’s roughly it,” said Joshua. “Except that time is a rigid stream and the different worlds are more firmly fixed in place than the driftwood on the river.