“‘Jailer, I’ll tell you an interesting fact. Everything we study, we modify by our study of it. Hence truth eternally eludes us.’
“He did not look convinced, just held out his hands for the plates.
“‘Take crabs, for example, I said ‘We poke them with a stick to see how they behave, and they behave as if poked by a stick.’
He folded his arms, the plates dangling from his fingertips.
“This is, of course, a very simple example,’ I said. Take a subtler example, such as atoms of light. Light, as you know, is one of the four great elements-in common parlance, fire. We study it by bouncing it off polished stones, or bending it in water, or squeezing it through holes. And how does it behave? It behaves as if bounced or squeezed or bent. We learn nothing, we merely cause events.’ I bent closer to him, waving my finger to keep his attention. ‘Has it occurred to you that sundials do not measure time, but create it?’ It had not, I saw. Time,’ I said,’is actually a thing, like porridge.’ I folded my arms and beamed at him, triumphant. The left side of his mouth twitched very slightly. He withdrew.”

From The Wreckage of Agathon, John Gardner – 1970