What does Krakauer mean by an “Emersonian high”?

Chris being described as "riding a giddy Emersonian high" means that he was ignoring posted warnings that said strictly forbidden area.

the primary theme of "elegy written in a country churchyard" is a reflection about the significance of the lives of a group of modest people buried in a rural church cemetery. elegies focus on the death of an individual or group of people, and they generally have a melancholy tone. hope this you all.