What does Muir accomplish in Paragraph 2?

The rarest and most beautiful of the flowering plants I discovered on this first grand excursion was Calypso borealis (the Hider of the North). I had been fording streams more and more difficult to cross and wading bogs and swamps that seemed more and more extensive and more difficult to force one's way through. Entering one of these great tamarac and arbor-vitae swamps one morning, holding a general though very crooked course by compass, struggling through tangled drooping branches and over and under broad heaps of fallen trees, I began to fear that I would not be able to reach dry ground before dark, and therefore would have to pass the night in the swamp and began, faint and hungry, to plan a nest of branches on one of the largest trees or windfalls like a monkey's nest, or eagle's, or Indian's in the flooded forests of the Orinoco described by Humboldt.