In a letter about Cuba, which Humboldt gives, he says:

The lands are high, and there are many very lofty mountains ...
all most beautiful, of a thousand different shapes, accessible
and covered with trees of a thousand kinds of such great height
that they seemed to reach the skies. I am told that the trees
never lose their foliage, and I can well believe it, for I
observed that they were as green and luxuriant as in Spain in the
month of May. Some were in bloom, others bearing fruit, and
others otherwise according to their nature. There were palm trees
of six or eight kinds, wonderful in their beautiful variety; but
this is the case with all the other trees; fruits and grasses,
trees, plants and fruits filled us with admiration. It contains
extraordinary pine groves and very extensive plains.

Humboldt here comments that these often-repeated expressions of
admiration prove a strong feeling for the beauty of Nature, since
they are concerned with foliage and shade, not with precious metals.
The next letter shews the growing power of description:

Reaching the harbour of Bastimentos, I put in.... The storm and a
rapid current kept me in for fourteen days, when I again set
sail, but not with favourable weather.... I had already made four
leagues when the storm recommenced and wearied me to such a
degree that I absolutely knew not what to do; my wound re-opened,
and for nine days my life was despaired of. Never was the sea
seen so high, so terrific, and so covered with foam; not only did
the wind oppose our proceeding onward, but it also rendered it
highly dangerous to run in for any headland, and kept me in that
sea, which seemed to me a sea of blood, seething like a cauldron
on a mighty fire. Never did the sky look more fearful; during one
day and one night it burned like a furnace, and emitted flashes
in such fashion that each time I looked to see if my masts and my
sails were not destroyed; these flashes came with such alarming
fury that we all thought the ship must have been consumed. All
this time the waters from heaven never ceased, not to say that it
rained, for it was like a repetition of the Deluge. The men were
at this time so crushed in spirit, that they longed for death as
a deliverance from so many martyrdoms. Twice already had the
ships suffered loss in boats, anchors, and riggi