e, it will answer all demands, carrying
"the promise and potency of all terrestrial life." If the measure of
the required "change in our notions" had been specified, the
proposition would have had a real meaning, and been susceptible of a
test. It is easy travelling through the stages of such an hypothesis;
you deposit at your bank a round sum ere you start, and, drawing on it
piecemeal at every pause, complete your grand tour without a debt.'

The last paragraph of this argument is forcibly and ably stated. On
it I am willing to try conclusions with Mr. Martineau. I may say, in
passing, that I share his contempt for the picturesque interpretation
of nature, if accuracy of vision be thereby impaired. But the term
Vorstellungs-faehigkeit, as used by me, means the power of definite
mental presentation, of attaching to words the corresponding objects
of thought, and of seeing these in their proper relations, without the
interior haze and soft penumbral borders which the theologian loves.
To this mode of interpreting nature' I shall to the best of my ability
now adhere.

Neither of us, I trust, will be afraid or ashamed to begin at the
alphabet of this question. Our first effort must be to understand
each other, and this mutual understanding can only be ensured by
beginning low down. Physically speaking, however, we need not go
below the sea-level. Let us then travel in company to the Caribbean
Sea, and halt upon the heated water. What is that sea, and what is
the sun that heats it? Answering for myself, I say that they are both
matter. I fill a glass with the sea-water and expose it on the deck
of the vessel; after some time the liquid has all disappeared, and
left a solid residue of salt in the glass behind. We have mobility,
invisibility--apparent annihilation. In virtue of

The glad and secret aid
The sun unto the ocean paid,

the water has taken to itself wings and flown off as vapour. From the
whole surface of the Caribbean Sea such vapour is rising: and now we
must follow it--not upon our legs, however, nor in a ship, nor even in
a balloon, but by the mind's eye--in other words, by that power of
Vorstellung which Mr. Martineau knows so well, and which he so justly
scorns when it indulges in loose practices.

Compounding, then, the northward motion of the vapour with the earth's
axial rotation, we track our fugitive through the higher atmospheric
regions, obliquely across the Atlantic Ocean