Thanks to Ricky Gervais' latest HBO series, we may now have a single sentence of Ludwig Wittgenstein that the general public will recognize:
If a lion could talk, we could not understand him.
Beyond its potential for inspiring no end of jokes, this sentence may make the most vivid case for the theory that what we call "reality" is very much a subjective mental construct of every individual. Wittgenstein went as far as to suggest that those individuals do not necessarily have to be human; but his point was that we would never understand the lion because there would be almost no (if any) overlap between the lion's constructed reality and our own.
It turns out that, in the late nineteenth century, two French historians, C. V. Langlois and C. Seignobos, wrote a treatise on the study of history; and an English translation of their work, provided by G. G. Berry, was published in 1898. In the English text we find (actually, I found, thanks to Friedrich Hayek) the sentence:
If former humanity did not resemble humanity of to-day, documents would be unintelligible.
In other words we can only make sense of the Greek texts of Plato by virtue of the fact that, in some general sense of the concept, Plato was the same kind of human being then that we are today. In terms of lion problem, our constructed reality overlaps Plato's considerably, which is a primary reason why reading Plato can contribute to our own construction of reality.
This led me to wonder whether or not Wittgenstein might have seen the Langlois-Seignobos treatise in some language or another. Leafing through Allan Janik and Stephen Toulmin's Wittgenstein's Vienna, however, I discovered that Wittgenstein had written the following in one of his Tractatus notebooks:
What is history to me? Mine is the first and only world.
Of course, when he was working on the Tractatus, he probably had not yet come to grips with (let alone even considered) the theory of constructed reality. His constructed reality was, to him at least, his "first and only world;" but, as he became more occupied with language, he realized that everyone had a "first and only world." The trick was how we could successfully communicate from such an isolated vantage point, and the substance of Philosophical Investigations began to emerge from this paradox. Nevertheless, it is ironic that, before there were lions, there were French "metahistorians!"