There are so many ways in which one might learn from the late Alistair Cooke but, whilst reading his piece of the recently-deceased (when the Letter was written) Duke Ellington, the following occured to me:
i. The authority with which he seemed to speak came, at least in part, from his personal knowledge on the people & places he was referring to. Commenting on the Duke's funeral service, he compares the sound of the huge congregation rising to its feet to "the several million bats whooshing out of the Carlsbad Caverns in New Mexico at the first blush of dawn". Within a few short paragraphs he is referring to obscure American towns such as Four Forks, Arkansas and New Iberia, Louisiana with easy recall. He had been there. He had heard the bats and tasted the obscurity. There is no substitute for personal knowledge. And it shows as a person speaks.
ii. His words were carefully chosen for the time in which he lived and the audience to which he was speaking. They would not all remain appropriate today. For example, in this letter he refers many times to Negroes; I'm sure that as his letters continued and as times changed he went on rather to refer to the same people as 'Blacks'.
iii. He was clearly fallible in his judgements and not without a degree of self-interest and self-promotion in what he said and how he said it. As sons of Adam do.