There was a city, made from knowledge sure and unexamined, and inhabited by ideas. It could not bear the weight of seeing, but it bore up another city, inhabited by people and made from matter, which covered and protected it, and took it as a foundation. Each from the other took its substance and safety. People from the city of matter bored holes down into the city of ideas, trying to see down, trying to understand what their lives were built on. And because the cities were so large, and the holes so small, the holes did no real damage to either city or its inhabitants. People looked down into them and saw bright vague shapes, and told their friends what they had seen, but neither city grew unsteady or tainted.
The city made of matter had the problems of matter, though, and one day it grew hungry. Its people grew hungry, its rulers grew hungry, even its dogs and cats and pigeons starved, and one day one of its people bored a hole down into the city of ideas. In his hunger he sought not just knowledge, but sustenance, and so he put his hand down into the hole and drew out an idea, struggling and shimmering, into the sunlight. It let out a wail, mourning itself for being lost and being seen, and it began to wither and become corrupt. The citizen heard and saw, but he did not care. He thrust it down his throat.
Others in the town saw that the citizen had bored a hole down to the city of ideas, and drawn out food. They, too, sought to feed themselves in this way. Their stomachs grew large and fat, but their hunger grew with their stomachs, even though the ideas had filled them to bursting. Having harvested all they could from the holes they had drilled, they divided their own citizenry into camps: one of eaters and one of meat. When the camp of meat was empty, they set out to find new cities of matter, with citizens of their own. At this all the neighboring cities resolved to mete out punishment. They prepared a ball of fire, all-devouring and inwhirling, and placed it upon the city.
The fire burned through the city of matter. It laid bare the ground and then broke through into the city of ideas. The city of ideas burned up and the fire began to spread, out and around into neighboring cities of ideas, and breaking through into other cities of matter it began to mix up the earth and both cities, poisoning each with each. The surviving citizens lost their unexamined understanding of things. They lost their ways of seeing and speaking to one another, of reading and understanding each other. They lost their own names and the ground under their feet. Some of them died. The rest made balloons, of lofty gases or heated air. They watched shards of ideas drift by in the churning ash-filled air, screaming and trying to hide as they drifted by, and they passed the time by catching them in nets. They pinned them to cards, which they pinned to cards, which they pinned to cards, and they laughed, and they waited.