David Dylan Thomas asked, "When was the last time in human history when you could have possibly consumed every piece of culture than had ever been created?"

In a realistic sense, you'd have to name a "sphere" of culture to do this as the link between even the occidental and the oriental was not well established such that a western scholar, for example, may have possibly known about "all" culture until modern times - and then being able to consume it all would be nearly impossible.

Within the much smaller realm of mathematics, the last mathematician who was said to have known "all" of mathematics was David Hillbert around 1900-1910. No modern mathematician functions in all of the various branches the way he and many of his predecessors did.

Given that there are currently over 7,000 "distinct" languages on the planet and they're dying at an increasing rate, if we surmise that there were at most 2x this number at the peak number of languages (which is a laughable guess at best), just knowing all these languages fluently would be a massive hurdle at best, much less all the culture raining down from each of them.