To understand "The Souces of Soviet Conduct" it is necessary to have some understanding of the individual who wrote it. Fortunately from a very early age the author kept a diary that continued throughout his very long life. At some point the author acquired a passion and perhaps even an obsession with Russia, differentiating between the Russian people, of whom he admired, and the Soviet communist system that ruled them, which he despised.
Sometimes fortune smiles on an individual. The author became a Foreign Services Officer, an occupation he often ridiculed, found incessantly boring and intellectually and morally unfufilling and wanted to quit. But the State Department in it's wisdom sent him to a special school to study the Russian language and pre-1917 Russian history (which the Bolsheviks wanted to cancel), and then sent him to Moscow, where he served two separate tours, the second begining in 1944 and from here on February 22, 1946 at 9 pm he sent "The Long Telegram" of over 5000 words that in its abridged form became "The Sources of Soviet Conduct."
Much of both can be found in his diary entries. For example, writing in June 1945, one month after Germany surrendered, "(T)here is no way of helping the Russian people. When a people places itself in the hands of a ruthless authoritarian regime which will stop at nothing, it places itself beyond the powers of others to help."
This represents the author's argument in miniature; namely, the long term patient and vigilant containment of Soviet communism. As explained by Professor Adam Ulam decades later, external change in the Soviet Union would be driven by internal change. This is what finally took place beginning in the mid-1980s.