DOWNWARD TO THE EARTH, by Robert Silverberg, 1970.

My copy is SF Masterworks #56, from a series of British reprints of out-of-print science fiction classics. The books in the series are a little bigger than mass market size, and all have extremely vivid covers.

This novel was originally serialized in Galaxy Magazine, and nominated for Nebula Novel on 1970.  Robert Silverberg withdrew from the nomination, and eventually Larry Niven's Ringworld won the award.   Does anybody know the story behind that?  So now this is a minor classic which has become somewhat obscure.

It tells the story of a former colonial administrator returning to the now relinquished Holman's World. Now known as Belzagor, the predominantly jungle planet is governed by two intelligent native peoples: the elephantoid nildoror, and bi-pedal sulidoror. In some ways, the prose reads like a precursor to China Mieville's Perido Street Station, with its nightmarish flora and fauna and sparse human inhabitants. But the real story is Gundersen's quest for the mythical mountain of nildoror rebirth, driven by his own need for moral and emotional redemption. The impact would be stronger if some of the other humans were developed more, but the book is short enough to get away with being a single character narrative. It's worth reading just for the imagery.