He’s often compared to Thoreau and John Muir.

Words describe him: scientist, professor, environmentalist, forester, ecologist.

But his writing — and his astonishing ideas — rise above all description.

Aldo Leopold was born in Iowa in 1887 and died fighting a grass fire on a neighboring farm, in Wisconsin. 1948. He had just become an advisor to the United Nations on conservation.

(There will be more on Aldo Leopold, when in July I will visit the Aldo Leopold Nature Center, in Monona, Wisconsin.)

I will never forget when I was introduced to his work, in 2000. I had never heard of him. Now his best-known book is a holy text to me — and to millions of others.

This is the book, published just after his death. In it is an essay, “Thinking Like a Mountain.” I will never forget this line:

Only the mountain has lived long enough to listen objectively to the howl of a wolf.