4 ideas
A strong writer does not merely inherit a tradition; their work changes how earlier texts are read, so that a shared quality in otherwise unrelated predecessors only becomes visible once the later writer exists. Without Kafka, the Kafka-like trait in Zeno's paradox, Kierkegaard, and Browning would go unnoticed, because it is the later work that picks out the common thread. Influence therefore runs backward as well as forward.
Coleridge imagined a man who crosses paradise in a dream, receives a flower as proof he was there, and wakes holding it. He also notes that a palace built by Kublai Khan was itself said to have been designed from a dream. Borges uses the chain to raise the possibility that one archetype is being revealed in stages through successive dreamers who do not know of each other.
Berkeley denied that matter exists apart from perception, and Hume went further and denied a continuous self beyond a series of perceptions. Borges argues that the same reasoning should deny time as a single sequence, since two identical moments, such as the same experience felt by two people or at two dates, are the same moment. He then concedes that the argument fails emotionally: 'Time is a river which sweeps me along, but I am the river.'
Borges suggests that universal history may be the history of how a few metaphors are expressed in different ways. His example is the image of the infinite sphere whose center is everywhere and whose circumference is nowhere. It passes from Xenophanes through Alan of Lille to Pascal, and its emotional tone changes with each age, from a picture of divine perfection to a source of terror at infinite space. Following one image through time shows how each era's mood reshapes an idea that stays the same in form.