How do you define "nature?" If we define it as that which is untouched by humans, we won't have any left, says environmental writer Emma Marris. She urges us to consider a new definition of nature -- one that includes not only pristine wilderness but also the untended patches of plants growing in urban spaces -- and encourages us to bring our children out to touch and tinker with it, so that one day they might love and protect it. TEDTalks is a daily video podcast of the best talks and performances from the TED Conference, where the world's leading thinkers and doers give the talk of their lives in 18 minutes (or less). Look for talks on Technology, Entertainment and Design -- plus science, business, global issues, the arts and much more. Find closed captions and translated subtitles in many languages at www.ted.com/translate Follow TED news on Twitter: www.twitter.com/tednews Like TED on Facebook: www.facebook.com/TED Subscribe to our channel: www.youtube.com/user/TEDtalksDirector