This started as a question, but along the way I sort of answered it myself.

Even among history's great scientific-minds, Einstein stood alone. There are super-intelligent people among us today, but they will never have the recognition that he attained. One of the reasons for his remarkable achievements in so many fields, was the fact that scientific-knowledge was still coming off a low base. To come up to 'speed' today, scientists must spend perhaps a decade or so studying the knowledge-base, and then specialise in a single discipline. Intimidating thought!