As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality. -- Albert Einstein
Mathematics would certainly have not come into existence if one had known from the beginning that there was in nature no exactly straight line, no actual circle, no absolute magnitude. -- Friedrich Nietzsche
I don't know what predominates in Cantor's theory - philosophy or theology, but I am sure that there is no mathematics there. -- Kronecker
In mathematics you don't understand things. You just get used to them. -- John von Neumann
There's no sense in being precise, when you don't even know what you're talking about. -- John von Neumann
Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality. -- Nikola Tesla