well, looking around this audience tonight, i suspect most of you know who rachel carson is, but i can tell you generally that is not the case with a lot of people. baby boomers and people older than baby boomers tend to remember carson and her work and young people in high school college are studied rachel carson and environmental studies classes and they are more likely to know who rachel carson us. but in between is this great doughnut hole. lots and lots of people who don't know rachel carson, don't know "silent spring" and as a result don't understand the origins of the environmental movement and as importantly, the debate and arguments we have around the environmental movement. they have their origins in "silent spring" and the reaction to "silent spring" in the historical context in which carson was working. these are questions that interested me alive. this is part of the reason i wrote a book about rachel carson. i wanted to understand where this movement came from, the role that she played in it and why we have this party sentiment of a safe, right left argument all the time

. >> up next, on a second look, remembering two environmental champion, john muir and rachel carson. all straight ahead on a second look. good evening and a welcome, i am julie haner. tonight we remember two environmentalist, and rachel carson's book silent spring and john muir bfs book's book the yosemite and wat an watson brought us this history in 2000 of yosemite. >> molding and carving yosemite. the signature on this sculpture was written by a 60 long glacier that chisels its way leaving yosemite valley in its wake. half dome, and all this right here in this small valley is almost too much to take in. it is enormous and about the size of the state of rhode island. almost 4 million people visited last year and you might be tempted to ask are we loving yosemite to death? greedy ravages of man have been the big threat. >> what we have here in yosemite, we have the best of the best and the worst of the wours. we have the scenery and the water falls and 800 miles of hiking trails. but we have hoards and hoards of people coming. so i think john muir never advocated keeping people out.