Here is how Kant put it in his Critique of Pure Reason. Whatever we think or perceive can register as a thought or perception only if it causes a change in us, a “modification of the mind.” But these changes would not register at all if we did not connect them across time, “for as contained in one moment no representation can ever be anything other

Specifically, Kant wrote, we can picture reality as being consistent and continuous, or as being broken into discrete chunks, and we can make perfectly logical and coherent arguments supporting both conclusions even though those conclusions explicitly contradict each other. This happens because we assume something about reality that only comes into

what Heisenberg grasped—what he calculated mathematically, yes, but also what he was able to capture in language—was that to simultaneously observe an electron’s position and momentum would require a perfect presence in a single moment in time, which is utterly incompatible with the minimum condition of observing anything at all. Not because of

To have a self, to experience anything at all, required the existence of the vast totality of space around him, of a past preceding him and a future yet to come. And yet that secret, hypothetical object, the inconceivable universe, was destined to remain hypothetical, secret, forever.

Indeed, it would be fair to say that the relationship with Norah had provoked some uncharacteristic writing on Borges’s part. Carlos Mastronardi, a fellow writer and friend, would later recall that for one of the few times in his life Borges seemed to have little desire to be anyone other than himself.

In so doing he reveals the very insight that ignited Kant’s revolution in thought: an observation of the world can never be perfectly of the world; it always requires something else, the insertion of a minimal distance that permits it to become knowledge in the first place.

Funes, Borges soon realized, lacked the basic function that permits us to think in the first place—abstraction. “Not only was it difficult for him to see that the generic symbol ‘dog’ took in all the dissimilar individuals of all shapes and sizes,” Borges recounts, “it irritated him that the ‘dog’ of three-fourteen in the afternoon, seen in

The more precisely you relive the past, the less it is a past you remember, and the more it becomes the present, vanishing before your eyes as the present always does. A truly perfect replay would erase its very sense of being a replay altogether because it would erase the connection between moments of time that constitute the one remembering, the

But our perceptions, Kant realized, aren’t things in the world; rather, they are versions of those things that we construct in our minds by shaping them in space and time. When we imagine the world as being identical to our conception of it—when we assume, specifically, that space and time are fundamentally real—our reason becomes faulty, and