Polymath. From the Greek polumathes. Polu or poly meaning many. And math meaning to learn. Thus the term means someone who has literally “learned much.”
The most common example of a polymath would be Leonardo da Vinci, a master not only of painting and sculpture but engineering and the sciences. It's the idea of the Renaissance Man or the Uomo Universalis- someone who is the sum of a society's learning. And one who attempts to know as much as possible about all that can be known. However, the trend in societies and technologies is towards ever greater specification. As the pool of knowledge expands those who attempt to understand are driven into specializations. Niches, if you will, where their knowledge can truly blossom. Those who attempt to generalize are left behind and bereft of the true depth of learning they need to comprehend let alone compete. Yet, at the same time, those who narrow their focus into their own pursuits can easily lose sight of all others. Becoming trapped in a stovepipe of their own making they feed out only what they've preselected to feed in. And it's only those who take a broad view of things who might be able to see the forest for the trees. It's the polymath who can step outside the boundaries of the niche and perform the necessary synthesis of creation. Yet as they create they add to the knowledge that everyone who comes after will have to learn in order to progress further – making it less likely for another polymath to emerge. But, then, learning becomes trapped looking backwards and not towards the potential futures of progress as the polymath, like Big Brother, becomes buried under a torrent of information. Synthesis, then, in the modern age comes not from those who “learn” much or are capable of mastering many disciplines but from those who experience much and flit from one niche to the next. And, of course, leaving connections behind that others can follow.