What is the effect of the word “atom” in this line and later in the poem?

(1) fire extended humans’ geographical boundaries by allowing them to travel into regions that were previously too cold to explore. (2) it also kept predators away, allowing early humans to sleep securely. (3) fire, in fact, has been a significant factor in human development and progress in many ways. (4) other obvious benefits of fire are its uses in cooking and in hunting. (5) probably even more important, however, is that learning to control fire allowed people to change the very rhythm of their lives. (6) before fire, the human daily cycle coincided with the rising and setting of the sun. (7) with fire, though, humans gained time to think and talk about the day’s events and to prepare strategies for coping with tomorrow. the sentence that expresses the main idea is: (type the number of the sentence. then click “go.”)

Armed with invisible ink, a cipher system, and a passion to end the war and preserve the union, elizabeth van lew became butler's eyes and ears in the confederate capital city. truth be told, however, she became much more than that. she became a spymaster, the person responsible for running a network of agents, couriers, and safe houses that was very active during the war. in addition to the spying, elizabeth van lew continued to maintain her church hill home as a safe house and something of a local union spy headquarters. —the dark game, paul janeczko what is the central idea of this passage? van lew’s home was used as a safe house, which was critical to the confederacy. van lew had a passion to end the war and preserve the union. van lew was a spymaster, a leading force in the espionage activities for the union. van lew did not enjoy working for general butler.

What is the message? how does langston hughes convey the message in this poem?