Answer the question at the end by quoting:

Walter Bendix Schonflies Benjamin (German: ['valta 'benjami:n]; 15 July 1892 - 26 September 1940) was a German Jewish philosopher, cultural critic and essayist. An eclectic thinker, combining elements of German idealism, Romanticism, Western Marxism, and Jewish mysticism, Benjamin made enduring and influential contributions to aesthetic theory, literary criticism, and historical materialism.
Theses on the Philosophy of History is often cited as Benjamin's last complete work, having been completed, according to Adorno, in the spring of 1940. The Institute for Social Research, which had relocated to New York, published Theses in Benjamin's memory in 1942. Margaret Cohen writes in the Cambridge Companion to Walter Benjamin: In the "Concept of History" Benjamin also turned to Jewish mysticism for a model of praxis in dark times, inspired by the kabbalistic precept that the work of the holy man is an activity known as tikkun. According to the kabbalah, God's attributes were once held in vessels whose glass was contaminated by the presence of evil and these vessels had consequently shattered, disseminating their contents to the four corners of the earth. Tikkun was the process of collecting the scattered fragments in the hopes of once more piecing them together. Benjamin fused tikkun with the Surrealist notion that liberation would come through releasing repressed collective material, to produce his celebrated account of the revolutionary historiographer, who sought to grab hold of elided memories as they sparked to view at moments of present danger. In the essay, Benjamin's famed ninth thesis struggles to reconcile the Idea of Progress in the present with the apparent chaos of the past: A Klee painting named Angelus Novus shows an angel looking as though he is about to move away from something he is fixedly contemplating. His eyes are staring, his mouth is open, his wings are spread. This is how one pictures the angel of history. His face is turned toward the past. Where we perceive a chain of events, he sees one single catastrophe which keeps piling wreckage upon wreckage and hurls it in front of his feet. The angel would like to stay, awaken the dead, and make whole what has been smashed. But a storm is blowing from Paradise; it has got caught in his wings with such violence that the angel can no longer close them. The storm irresistibly propels him into the future to which his back is turned, while the pile of debris before him grows skyward. This storm is what we call progress. The final paragraph about the Jewish quest for the Messiah provides a harrowing final point to Benjamin's work, with its themes of culture, destruction, Jewish heritage and the fight between humanity and nihilism. He brings up the interdiction, in some varieties of Judaism, to try to determine the year when the Messiah would come into the world, and points out that this did not make Jews indifferent to the future "for every second of time was the strait gate through which the Messiah might enter."

What is important about the dark times?

Answer the question at the end by quoting:

Robert Swan Mueller III (; born August 7, 1944) is an American attorney who served as the sixth Director of the Federal Bureau of Investigation from 2001 to 2013. A Republican, he was appointed by President George W. Bush; President Barack Obama gave his original ten-year term a two-year extension, making him the longest-serving FBI director since J. Edgar Hoover. He is currently head of the Special Counsel investigation of Russian interference in the 2016 United States elections and related matters. A graduate of Princeton University, Mueller served as a Marine Corps officer during the Vietnam War, receiving the Bronze Star Medal with Combat "V" for heroism and the Purple Heart Medal.
Mueller was accepted for officer training in the United States Marine Corps in 1968, attending training at Parris Island, Officer Candidate School, Army Ranger School, and Army jump school. In July 1968, he was sent to South Vietnam, where he served as a rifle platoon leader with Second Platoon, H Company, 2nd Battalion, 4th Marines, 3rd Marine Division. In December 1968, he earned the Bronze Star with 'V' distinction for combat valor for rescuing a wounded Marine under enemy fire during an ambush that saw half of his platoon become casualties. In April 1969, he received an enemy gunshot wound in the thigh, recovered, and returned to lead his platoon until June 1969. For his service in and during the Vietnam War, his military decorations and awards include: the Bronze Star Medal with Combat "V", Purple Heart Medal, two Navy and Marine Corps Commendation Medals with Combat "V", Combat Action Ribbon, National Defense Service Medal, Vietnam Service Medal with three service stars, Republic of Vietnam Gallantry Cross, Republic of Vietnam Campaign Medal, and Parachutist Badge. Mueller eventually became aide-de-camp to 3rd Marine Division's commanding general, then-Major General William K. Jones, where he "significantly contributed to the rapport" Jones had with other officers, according to one report. Reflecting on his service in the Vietnam War, Mueller said, "I consider myself exceptionally lucky to have made it out of Vietnam. There were many--many--who did not. And perhaps because I did survive Vietnam, I have always felt compelled to contribute." After returning from Vietnam, Mueller was briefly stationed at Henderson Hall, before leaving active-duty service in August 1970. He was inducted into the Ranger Hall of Fame in 2004.

What did he do after training?
In July 1968, he was sent to South Vietnam, where he served as a rifle platoon leader