In 1910 Bertrand Russell and Alfred North Whitehead published book Principia Mathematica in which on page 360 they came to conclusion that 1 + 1 = 2
And looking on us I think we all are doing the same: having doubts if that’s true we are generating long chain of reasonings to come to the original thought why it is so. The difference between “before” and “after” is that we have the proof why it is so. Each of us may have different proof, but we increase overall understanding of the same.