nning along the grain, and sometimes by way of the
side, by means of a curved road cutting across the grain.

Is the compass a chemical influence, or electrical, or calorific, or
what not? No, for in an upright trunk the emergence is effected as
often by the north face, which is always in the shade, as by the south
face, which receives the sun all day long. The exit-door opens in the
side which is nearest, without any other condition. Can it be the
temperature? Not that either, for the shady side, though cooler, is
utilized as often as the side facing the sun.

Can it be sound? Not so. The sound of what, in the silence of
solitude? And are the noises of the outside world propagated through
half an inch of wood in such a way as to make differences perceptible?
Can it be weight? No again, for the trunk of the poplar shows us more
than one Sirex travelling upside down, with his head towards the
ground, without any change in the direction of the curved passages.

What then is the guide? I have no idea. It is not the first time that
this obscure question has been put to me. When studying the emergence
of the Three-pronged Osmia from the bramble-stems shifted from their
natural position by my wiles, I recognized the uncertainty in which
the evidence of physical science leaves us; and, in the impossibility
of finding any other reply, I suggested a special sense, the sense of
open space. Instructed by the Sirex, the Buprestes, the Longicorns, I
am once again compelled to make the same suggestion. It is not that I
care for the expression: the unknown cannot be named in any language.
It means that the hermits in the dark know how to find the light by
the shortest road; it is the confessions of an ignorance which no
honest observer will blush to share. Now that the evolutionists'
interpretations of instinct have been recognized as worthless, we all
come to that stimulating maxim of Anaxagoras', which laconically sums
up the result of my researches:

"[Greek: Nous panta diekosmese]. Mind orders all things."

CHAPTER IX
THE DUNG-BEETLES OF THE PAMPAS

To travel the world, by land and sea, from pole to pole; to
cross-question life, under every clime, in the infinite variety of its
manifestations: that surely would be glorious luck for him that has
eyes to see; and it formed the radiant dream of my young years, at the
time when _Robinson Crusoe_ was my delight. These rosy illusions, rich
in voyages, were soon succeeded