He is not the first to notice that Europe is a narrowish peninsula - even a peninsula of peninsulas - projecting west from Asia, but I don't think I have read anyone hitting the observation quite so hard or drawing so much from it. Usually, when that framing is used Scandinavia is included and sometimes even Turkey. I'd like to look at this a little differently at the moment. There are two very complicated coastlines to Europe in this picture: one in the south from the Black Sea, through the Bosporus, through many islands on the way to Gibraltar and the Atlantic; the other from Portugal through two narrow channels up to the Gulf of Finland. Ignore the lands across from these coasts at the moment, no matter how close (though you can keep all the islands in those seas as part of the picture). We will bring them back in a bit.
The peninsula can be transversed almost entirely by navigable rivers in many places. The Danube and the Rhine you likely knew about. The Loire and the Rhone you may have been aware of if you studied French history. But there are many other places, as short as 300 miles just above the Pyrenees, and as far up the peninsula as the Dniepr and the Don, where the crossing is still only a bit over 800 miles. The rivers emptying into the Baltic, the Dvina, the Vistula, and the Nemunas, are not as wide and navigable, but still sizable. Treat it as optional whether you include the Volga, which flows into the Caspian and was later used by the Swedish vikings, but was less of an influence on the rest of the peninsula. (Note that current political boundaries are on this map, though faint. I am considering my beginning-of-Europe boundary as running along the eastern boundaries of the Baltic States, along Belarus, and bisecting Ukraine.)
For a long while after the Little Dryas cooling period (about 10,000 BC), all of this complicated area was still mostly subsistence living, foragers and hunter-gatherers. It is important to note that these are diverse environments, with various groups settling islands, coves, littorals and fens, on up rivers to hills and mountainsides. As technology improved, there began to be trade, along coasts and up rivers. Domesticated animals and crop farming start to come in. The time periods seem long to us now, but the exchange of technology and goods accelerated precisely because there were so many varied adaptations to the incredible diversity of ecological niches. Complexity of environment leads to shared technological improvement, which leads to increased population and prosperity, which leads to...well, it leads to war, hierarchy and government, which would seem to be a high cost, but one folks everywhere have seemed willing to pay. The verticality of Peru created enormous variations in environments in just a few miles, leading to the Incas. From where the Yellow River of China empties into the Yellow Sea is complicated coastline for hundreds of miles in both directions, and this area was also a source of innovation. The fertile crescent was not only good for growing things, it had contact with disparate cultures in many directions. The Tigris and Euphrates reach almost to the Mediterranean and even the Black Sea, but flow into the Arabian Sea, opening out to a different world of cultures.
But because of a late start owing to the glacier and then the Little Dryas. it took a while for Europe to catch up. But catch up it did and the spread of technology fed on itself to create more and more extensive trade networks. Now let us add the other sides of those seas back into the picture, the coast of North Africa, Great Britain, and Scandinavia. The European peninsula did not know the interiors of those facing lands, they knew them mostly as ports. But they didn't need much else. The complicated cultures that were growing up on the peninsula(s), the LBK and Corded Ware did not much penetrate those lands across the seas, just a bit of southern Sweden and Norway. Even the later Indo-European culture, which came to dominate all of Europe, did not penetrate across water very well until much later.
The great cities and civilisations do not spring up in places of similar surrounding environments but at the intersection of them, where people can bring goods like tin, amber, wine, or metalwork that is not available everywhere. There may have thus been an inevitability to the rise of Europe once it got untracked. If we replayed the prehistory a dozen times each might look different, but I think in all cases we would have seen this rise in complexity, prosperity, and population.