Miłosz's exploration of morality takes place in the context of history, and confrontation with history is another of his major themes. Vendler wrote, "for Miłosz, the person is irrevocably a person in history, and the interchange between external event and the individual life is the matrix of poetry". Having experienced both Nazism and Stalinism, Miłosz was particularly concerned with the notion of "historical necessity", which, in the 20th century, was used to justify human suffering on a previously unheard-of scale. Yet Miłosz did not reject the concept entirely. Nathan and Quinn summarize Miłosz's appraisal of historical necessity as it appears in his essay collection "Views from San Francisco Bay": "Some species rise, others fall, as do human families, nations, and whole civilizations. There may well be an internal logic to these transformations, a logic that when viewed from sufficient distance has its own elegance, harmony, and grace. Our reason tempts us to be enthralled by this superhuman splendor; but when so enthralled we find it difficult to remember, except perhaps as an element in an abstract calculus, the millions of individuals, the millions upon millions, who unwillingly paid for this splendor with pain and blood".