that is what you see henry david thoreau doing.e casts himself as a world explorer and he says i am home. i will do the humboldt 11e n exploration right here and as the explorer sees but without leaving home. without leaving home and collecting objects, henry david for a collect arrowheads and plants and so on, measuring again, he was famously out measuring a stream and counting tree rings and systematic work and to the goal of connecting so it is a distinct methodology. this is humboldtian science and the cutting edge of science and it had particularly powerful play in the united states where exploration, that was what we needed to be doing and he gave that methodology. so henry david thoreau applies that to this home base in an exciting and original way. >> could you go back to the world map for a minute? the world map. i missed what this world map is subject -- was the subject of this map -- >> this is plant geography. the mountains across the top, humboldt wrote in the essay on geography of plants that has never been fully tran

my interest started when i was working on henry david thorough as a graduate student, and i was curious how he had found a model for the work he was doing in natural sciences, and it seemed to me that contemporary scholarship didn't have the answer to that. i was taking a seminar in the works of charles darwin. the professor dropped a heavy tome on our laps and said, read this. darwin did. and i did. it was alexander von humboldt's personal narrative. and i thought, my gosh, this is it. it has to be humboldt, and so that was the start of a very, very long quest that's still going on today into understanding humboldt's impact and influence in the united states which was quite broad. that turned out to be astonishing because every time i talk to people about humboldt, i got that glazed look. humboldt who? [laughter] and so part of my mission has been to, well, to explain something about humboldt who, how wonderful and important he was. so just a very, very quick thumbnail introduction to him here. joel also gave some useful information. i love this photograph because he looks so warm and