I have long been wondering about working mechanism of Ramanujan's brain. It seems to me that he'd been given some sort of mysterious intelligence that no one else ever had been. Even if one regards it as merely capability of numeric calculation, the level he reaches (so high that allows him to deduce $1/\pi=2\sqrt2/9801...$ kind of stuff) is still far beyond that of those mathematicians-including the monumental ones like Euler, Gauss and Riemann-known for their calculating power and perserverance. I don't believe in his explanation that he gets all these from Goddess but could not even think of a reason of existence of a human who is capable of doing so. This man is never academically well-trained (from his papers it's evident that even after starting cooperation with Hardy he still thinks and 'feels' in his own way) but produces the most unexplainable formulas a large portion of which is shown to be essential in-and should arise naturally when the time comes, from-arithmetic geometry, a discipline he'd definitely never ever heard of in his whole life several decades later! How can this happen! It seems plausible that all mathematical insights and technical developments, however brilliant, profound and complicated as those of Riemann's and Grothendieck's, are able to be descripted by ingenuity of inspecting the correct mathematical structures and connections between them and expressing them in correct ways, but this does not work for case of Ramanujan. His type of reason-transcending 'instinct' differs from the usual meanings of mathematical intelligence so much that in a rigorous sense he's never a mathematician, notwithstanding the fact that he'd contributed to the society so much during and after his lifetime!
Question: Can anyone suggest a promising explanation of the origin and mechanism of Ramanujan's intelligence? I can't find answer from his biographies and am also not yet aware of higher mathematics (e.g. automorphic forms) that are related to his work, and don't even know whether this problem is most suitable for specialists in these fields or those know more about neorology and/or 'supernatural' phenomenons. But thanks in advance whatsoever.