it is better, for those who
wish to learn accurately, to see one thing twice than many things
once. A lesson is never learnt till it is learnt over many times,
and a spot is best understood by staying in it and mastering it. In
natural history the old scholar's saw of 'Cave hominem unius libri'
may be paraphrased by 'He is a thoroughly good naturalist who knows
one parish thoroughly.'

So back to our little beach we went, and walked it all over again,
finding, of course, many things which had escaped us the night
before. We saw our first Melocactus, and our first night-blowing
Cereus creeping over the rocks. We found our first tropic orchid,
with white, lilac, and purple flowers on a stalk three feet high.
We saw our first wild pines (Tillandsias, etc.) clinging parasitic
on the boughs of strange trees, or nestling among the angular limb-
like shoots of the columnar Cereus. We learnt to distinguish the
poisonous Manchineel; and were thankful, in serious earnest, that we
had happily plucked none the night before, when we were snatching at
every new leaf; for its milky juice, by mere dropping on the skin,
burns like the poisoned tunic of Nessus, and will even, when the
head is injured by it, cause blindness and death. We gathered a
nosegay of the loveliest flowers, under a burning sun, within ten
days of Christmas; and then wandered off the shore up a little path
in the red lava, toward a farm where we expected to see fresh
curiosities, and not in vain. On one side of the path a hedge of
Pinguin (Bromelia)--the plants like huge pine-apple plants without
the fruit--was but three feet high, but from its prickles utterly
impenetrable to man or beast; and inside the hedge, a tree like a
straggling pear, with huge green calabashes growing out of its bark-
-here was actually Crescentia Cujete--the plaything of one's
childhood--alive and growing. The other side was low scrub--prickly
shrubs like acacias and mimosas, covered with a creeping vine with
brilliant yellow hair (we had seen it already from the ship, gilding
large patches of the slopes), most like European dodder. Among it
rose the tall Calotropis procera, with its fleshy gray stems and
leaves, and its azure of lovely lilac flowers, with curious columns
of stamens in each--an Asclepiad introduced from the Old World,
where it ranges from tropical Africa to Afghanistan; and so on, and
so on, up to a little farmyard, very like