I am convinced that the act of thinking logically cannot possibly be natural to the human mind. If it were, then mathematics would be everybody's easiest course at school and our species would not have taken several millennia to figure out the scientific method.
He had a better mind and a more rigorous temperament than me; he thought logically, and then acted on the conclusion of logical thought. Whereas most of us, I suspect, do the opposite: we make an instinctive decision, then build up an infrastructure of reasoning to justify it. And call the result common sense.
Look, we are getting to be old men, and we've spent our lives looking for the weaknesses in one another's systems... Don't you think it's time to recognise that there is as little worth on your side as there is on mine?