inventions. These three discoveries made a long time ago continue to make the greatest impact on our world. (2) Early man observed fire as a natural and very frightening disaster that could destroy his environment and all that was in it, including himself. Over time, he learned how to tame it and use it for cooking and keeping himself warm in cold weather. Fire is now used extensively, even in ways that are not so obvious. For example, fire is an operating principle in all kinds of engines that have transformed modern life. Yet there remains a dark side. Weapons of all kinds utilize fire to enhance their capacity to kill and destroy on a scale previously unthinkable. The word mankind in Paragraph (1) is closest in meaning to ………….
The word mankind in Paragraph (1) is closest in meaning to