Please explain this in plain English.
It's about cultural differences. An American had been cooling his heels, and he told the minister who he wanted to meet via persons, and then the minister get unpleasant and said "let him cool his heels".
"To suggest to an American's secretary that perhaps her boss didn't know you were there after waiting sixty seconds would seem absurd, as would raising a storm about "cooling your heels" for five minutes. Yet this is precisely way the minister registered the protestations of American in his outer office!"