“For those awake there is one common world; but for those sleeping each deserts into a private world.” (here Sweet 89; cp. DK B89, K 6, WF T1)
“Heraclitus says that the universe for those who are awake is single and common, while in sleep each person turns aside into a private universe.” (Waterfield T1)
“The waking have one world in common, whereas each sleeper turns away to a private world of her own” (Wheelwright 15)
Given that understanding requires access to a world of meanings that each individual has available internally, one might wonder whether in understanding we in fact do the opposite of what Heraclitus here suggests — that is, we turn within ourselves and access the repertoire of meanings that we have come to individually accept.
In line with this view, which accords in large with various forms of expressionism since the 19th century and with some general ideas of postmodernism, each individual has a somewhat unique and private experience. If a biologist looks at a tree, she understands it in reference to a set of meanings that she as a biologist grasps but that an average painter would not. The painter by contrast might have an individually accented experience of the colors of the tree, because of sensitivities to light conditions as affecting the experience of color, and so on. It might seem that each has a separate world.
Yet, Heraclitus, who does see understanding as the key to awakening, stresses that those who understand are not caught in private worlds. To the contrary, it is those who fail to understand (the sleeping) who are caught in these. Evidently the views of the biologist and the painter would at least potentially be available to all. If true views, these would belong to a common world, not a private one. Objective statements of fact are able to be corroborated by others. They are thus not just private opinions. Rather, they are part of one true shared worldview that is at least in theory possible.
But how do we access this common world, or as the Waterfield translation emphasizes, this “single and common world”? The individual mind, as Heraclitus, sees it, or certainly as Plato later sees it, has a universe of ideas available to it. Each single “spark” of the divine fire, we might see as somehow connected to common flame. Each individual mind is connected to the universal mind. The sleeping too would be linked to the universal mind, but they would need to be awakened to this. While Heraclitus sees the universal mind as the shared mind, he does not seem open to the use of dialogue, as Plato will, or a contemporary like Habermas will, to achieve this understanding. His suspicion appears to be that an appeal to dialogue with the uninformed will lead to a stronger affirmation of collective illusions. A non-dialectically engaged collectivity would only engage in irrational group think.