Name the Artist: Mercedes Boy?

Questions

Who said 'So far as the laws of mathematics refer to reality they are not certain. And so far as they are certain, they do not refer to reality.'?

Who said 'The greater our knowledge increases, the more our ignorance unfolds'?

Who said 'The way of the warrior is the resolute acceptance of death'?

Who said the line 'Dr Livingstone, I presume!'?

Who took the title 'Lord Protector of the Commonwelth of England, Scotland, and Ireland'?