Why did Kovaly initially embrace Communism and then gradually reject the political ideology?

The author chronicles the divergence of ideological Communism and applied Soviet-style Communism during the early 1950s. Naturally, a fair amount of insightful commentary is included but the fundamental concept is that tyranny, in whatever form, is evil and destructive. The book ends with a prolonged political commentary on the Prague Spring of 1968 and the immediate results of that transient upheaval.