By this I mean to say: to reach out in my own way to the things I wished to learn, rather than relying on the notions of the consensus, overt or tacit, coming from a more or less extended clan of which I found myself a member, or which for any other reason laid claim to be taken as an authority. This silent consensus had informed me, both at the lyé and at the university, that one shouldn’t bother worrying about what was really meant when using a term like “volume”, which was “obviously self-evident”, “generally known”, “unproblematic”, etc. I’d gone over their heads, almost as a matter of course, even as Lesbesgue himself had, several decades before, gone over their heads. It is in this gesture of “going beyond”, to be something in oneself rather than the pawn of a consensus, the refusal to stay within a rigid circle that others have drawn around one – it is in this solitary act that one finds true creativity. All others things follow as a matter of course.
— Alexander Grothendieck, Récoltes et Semailles (1986)
The question you raise “how can such a formulation lead to computations” doesn’t bother me in the least! Throughout my whole life as a mathematician, the possibility of making explicit, elegant computations has always come out by itself, as a byproduct of a thorough conceptual understanding of what was going on. Thus I never bothered about whether what would come out would be suitable for this or that, but just tried to understand – and it always turned out that understanding was all that mattered.
— Alexander Grothendieck, Correspondence with R. Brown