In a story called The Library of Babel, Jorge Luis Borges describes an endless library filled with books with seemingly random contents. I view this as a thought-experiment in combinatorics: Every 300-page book that has ever been or ever will be written sits on a shelf somewhere in this library.
When we try to visualize it, the hypothetical size of Borges’s library is staggering: The number of rooms it must contain would be larger than the number represented by 1 followed by 100,000 zeroes. It would be as if every subatomic particle in the universe had its own universe with as many particles, and every particle in that universe had its own universe, repeating this down 1,000 levels, and at the bottom, each subatomic particle was a room in this enormous library.
In comparison, my construction is quite easy to imagine. A castle with maybe a hundred million rooms, though I haven’t been able to count, with an intricate network of hallways connecting them. The castle is large, but by no means infinite. It has so many rooms that no one has been able to catalog all of them, though not for lack of trying. The rooms vary in size. Most are the dimensions of a small bedroom, and many are little bigger than a closet. I’ve seen more than a few the size of an auditorium, though these are rather rare.
This castle is built into a mountain. Most of the rooms are deep in the mountain’s interior. If the mountain were a perfect cone, which it is not, it would be a mile and a half tall and 3 miles wide. The rooms and the tunnels and staircases connecting them –which take up more space than the rooms themselves– leave little space for the actual rock of the mountain, the majority of which has been mined away over the centuries.
No one has found two rooms that are exactly alike, though some vary in minor details. For example, one room might contain 19th century hunting rifles surrounding a full-size taxidermied African elephant. An adjacent room might be otherwise identical except the stuffed elephant is Indian. But in general, the rooms vary significantly. One enormous room larger than an airplane hangar contains a full scale replica of a Saturn V rocket amid space suits and operational Mars rovers. Another closet-sized room contains nothing other than a single monarch butterfly and a wall calendar. Some rooms are pristine and a pleasant temperature, others are filthy with polluted air and well below freezing.
There are two aspects every room has in common. First, there is a plaque above the door entering every room that has a seemingly random string of 20 letters. This label seems to be the room’s identifier in some bizarre index. Second, somewhere in every room there is a wall calendar.
Finally, the tunnels connecting the rooms are each lined with moving walkways such that a person may step out of one of the exits from one room and rapidly be whisked along over a mile of conduits to the entrance of another room.
The connections between the rooms don’t follow a simple pattern, but they are far from arbitrary. One can usually find a theme that any two connected rooms share. The small room with the monarch butterfly connects to rooms with other species of butterflies, and a larger room with a wide variety of insects, and several others.
This castle has a team of “caretakers” who, as a group, zip from room-to-room with the task of dusting the room, taking inventory, and, importantly, flipping the calendars on the wall to the current month. The team of caretakers is neither random nor systematic in the order in which they visit the rooms. The team of caretakers has existed for millennia, with new members apprenticing and eventually replacing the old. In a day, the team may visit several hundred rooms. Despite this, there are rooms that have not been visited for over a thousand years, and which are buried in layers of dust. (What process generates this dust is another mystery.)
The caretakers’ task is to prevent dust from building too much, and some rooms accumulate dust faster than others, which the caretakers have picked up on, and have duly modified their routes in accordance.
The more rooms the caretakers try to maintain, the dustier those rooms become. For several thousand years, the caretakers kept a nearly even visitation schedule, which resulted in the rooms being uniformly covered in a relatively thin layer of dust.
Better that some rooms are dust free and some very dusty, rather than every room having some dust. With this in mind, there were periods when the caretakers agreed to cordon off a small fraction of the castle, only about 10,000 rooms, less than a percent of a percent of the total, to be visited on a regular schedule. These rooms were each visited several times a year for a few decades. But this came at the expense of the other rooms being completely neglected: time kept marching, and the dust kept piling up ever higher.
Some speculate that the number of rooms in the castle has grown over the centuries, and that the existing rooms become rearranged from time-to-time. This is possible. The walkways are shut down every day after the caretakers have returned to their quarters for the evening. The caretakers are unable to venture far with the walkways out, so no one has been able to disprove that another crew or some other agent meddles with the rooms.
Some speculate further that the castle started much smaller, with only a few thousand rooms. If so, then a hundred years was enough time to clean each room many times. A caretaker could conceivably visit every room within their lifetime. Now, a century goes by and only a fraction of the rooms get cleaned. Though the caretakers tend to be long-lived, it’s inconceivable that a caretaker living today could visit any more than a tenth of the total rooms.
The purpose of the calendars is to help keep records of when the room was last visited. Another speculation is that rooms that have not been visited for a long time –a thousand years or so– become so filled with dust that the mysterious night crew completely repurposes them, sometimes closing off all tunnels into the neglected room. The caretakers, aware of this possibility ever scramble to preserve what rooms they can.
And so it is with my memories of Brussels, which remains frozen as it was over a decade ago, and my cousin who remains 5 years old, though she is no younger than myself.
They say that until the Renaissance, the collective scholarly knowledge of mankind was small enough that a single person could absorb it all. Was there ever such a point with mankind’s collective tacit knowledge? Probably not. Consider all the native detailed knowledge of flora and fauna in different regions. If there were such a point, then a person wouldn’t benefit much from being born much earlier because he’d already be on the cusp of human knowledge.
A person could learn almost every field, but it might take him 100 years, at which point, the earlier fields would have advanced. Some of the fundamentals would probably be the same, though. He would also probably forget a great deal, and, the way the human brain is constructed, would probably be overly influenced by his current context.
Possibly, after a point, since a person has limited memory, a person would simply be in a steady-state in a sense. That is, he wouldn’t remember his entire life, rather he’d keep living the same period over and over again because he couldn’t remember anything else. Perhaps Chimpanzees (or dogs) are like this too. After a certain point, they simply relive the same days over and over again, they get in a rut and become a (many-state) automaton.
 It’s unlikely that there is another crew of caretakers during the day. Though the likelihood of two crews running into each other on any given day is similar to that for winning a low-stakes lottery, after several centuries, the probability that they won’t run into each other becomes almost impossible.
 Bill Holstein once said that he can’t remember anything new because, to do so, he’d have to forget something he already knew, and, at his age (through a Darwinian process), almost everything he knew was really important.