Great Expectations, Charles Dickens, 1861
Zur Elektrodynamik bewegter Körper ("On the Electrodynamics of Moving Bodies"), A. Einstein, 1905
Of course he dashed off another three articles in the same edition of Annalen der Physik, all on the same level of comprehensibility, one of which scored him a Nobel prize.
The difficulty of relativity was and is a silly meme. The basic principles are straightforward. I understood them as a boy, and I am - by a regrettably enormous stretch - no genius.
I don't see two as a natural lower bound on the number of founders. As the productivity of individual programmers continues to rise, I expect to see an increasing number of single-founder startups succeed.