If you're willing to leave the standpoint of a 'reality' which is based in the interactions between 'subject' and 'object' then things get really interesting and you begin to question what such an apparently great man meant when he said that what was revealed to him was done so by divinity.
To do so, of course, would mean you would have to understand the metaphysics of Indian thought and culture, which may be (rather basically) summarised to hold that the objective is merely a reflection of the absolute Subjective, i.e. divinity.
This is especially important because it is from this cultural standpoint that these visions were realised. I could go on if anyone is interested.
A bit of background: I've spent the last three years of my life studying Indian metaphysics in India at a traditional academy known as an 'ashram'. The environment was somewhat similar to the original Greek academies, I can imagine, but that is speculation. I also have interests in tech, programming and philosophy. Please note that I am not trying to 'prove anything' either correct or incorrect -- indeed, this would not be the forum to do so. Rather, an opportunity to be of service to another individual and present two different views of this experience of the world and thus life itself.
For the western mind, indeed, for my mind -- it is ingrained to a point of 'truth' that there is a single objective world around us which presents itself to various individuals via the senses. It literally took me 1.5 years of serious mental deconstruction, analysis and questioning before I was able to entertain the thought that my body, brain and indeed the world around me were a _product_ of the mind, and did not produce the mind itself. Consider that. It's your whole system of thinking about the world turned upside down.
In building a metaphysical system for the world and individual, the Indians defined an individual as a 'body-mind-intellect' (BMI) experiencing 'perceptions-emotions-thoughts' (PET). The former they termed the 'relative subject' and the latter the 'relative object'. It is easy to see that these cover EVERY aspect of human experience.
I am taking a shortcut and would be happy to clarify further, but there is a facet of the spiritual path in India known as bhakti yoga (the science of union with the Divine through emotion) which targets the mind in its emotional capacity. It is not uncommon, then, to use an IDOL (which is NOT the same as the goal itself) to represent the goal of absolute subjectivity which one is striving for and cannot be perceived, felt or conceived via the BMI and their PET.
This representation, symbol, takes the form of a goddess/god whose strange and crazy figures and ornamentation are intended to initially (1) evoke questions in the seeker as t to their presence and (2) inspire more devotion once their significance is intellectually understood.
Coming back to the genius mathematician. If one traces one's own moments of lucidity or inspiration, one would find that they come at times when the mind is relatively calm, composed and engaged in a subject. The extrapolation of this is the state of bhakti yoga (complete absorption in the ideas represented by the deity), and most adherents thereto ascribe the 'doing' of their thoughts, words and deeds to the deity Itself, to efface their egos and move closer to their ideal of transcending the world itself.
Now look at that simple statement: "These ideas were revealed to me by my God" [paraphrase]. The simplistic notion that an apparition appeared before him or in his mind to provide him with these incredible insights does not hold to a scientifically-inclined mind. But the notion that he had trained his mind so highly that he was able to become absorbed single-thoughtfully upon a subject to the extent that he was able to perceive subtle nuances therein, indeed subtle nuances that would seem 'magical' to a non-trained observer is not unthinkable. That he then ascribed his discoveries to a deity is something that happens daily in Indian life and as previously covered is intended as an effacement and ultimate transcendence of the ego and the world it projects.
I can highly recommend A Parthasarathy's Vedanta Treatise if you are interested further.