Please help explain a quote from Tom Stoppard

Explanation. . . ? is a famous quote from Criminal Minds. . . Tom Stoppard (playwright, born in the Czech Republic in 1937, formerly known as Tom Sraussler. He traveled to the Czech Republic, Singapore, India and other places due to World War II in his early years, and settled in the UK with his stepfather at the age of ten): We walked to the bridge and crossed it straight. Turn around and burn again, burning away the evidence of moving forward, leaving only the billowing smoke in the memory and the eyes that may have been moist. Describe the aftermath of the war. Sorry for the inaccurate visual estimation