This letter was written for the Sixth Congress of the Comintern in July-August 1928. A new orientation of the Comintern had already been announced at by the Executive Committee of the Comintern in February 1928, under the title of "the Third Period".
1. What were the main features of the "Third Period" policy?
2. What turn of internal policy in the USSR was it linked to?
3. If this was the "Third Period", what had been the "first" and "second" periods?
4. In fact, as Trotsky shows in this letter, Comintern policy before 1928 had gone through more than two "periods". What were the main phases of Comintern policy before 1928?
5. Trotsky agrees that some shift to the left in the European working class is taking place in 1928 - he quotes himself from a document of December 1927, "On the New Stage" - but disputes the account of that given by the German CP leader Ernst Thaelmann. How?
6. Why does Trotsky think it impossible that the "Left" turn of the bureaucracy can be serious? Was he right about that?
7. Other texts, such as Ruth Fischer's "Stalin and German Communism", adduce other factors in the "Third Period".
See for example the reference in this review.
What do you make of this?
On the "Third Period", see further Trotsky's "The Third Period of the Comintern's Errors", an abridged version of which can be found on the web here.