e decomposition
or detritus of those stony substances; for, masses of looser sand and
softer substances contribute still more to the formation of vegetable
soils.

With regard to the other proposition, our author says, "Soil is not
constantly carried away by the water, even from mountains."--I have not
said that it is _constantly_ washed away; for, while it is soil in which
plants grow, it is not travelling to the sea, although it be on the road,
and must there arrive in time. I have said, that it is _necessarily_
washed away, that is, occasionally. M. de Luc's authority is then
referred to, as refuting this operation of water and time upon the soil.
Now, I cannot help here observing, that our author seems to have as
much misapprehended M. de Luc's argument as he has done mine. That
philosopher, in his letters to the Queen, has described most accurately
the decay of the rocks and solid mountains of the Alps and Jura, and the
travelling of their materials by water, although he does not carry them
to the sea. It is true, indeed, that this author, who supposes the
present earth on which we dwell very young, is anxious to make an earth,
_in time_, that shall not decay nor be washed away at all; but that time
is not come yet; therefore the authority, here given against my
theory, is the speculative supposition, or mere opinion, of a natural
philosopher, with regard to an event which may never come to pass, and
which I shall have occasion to consider fully in another place.

Our author had just now said, that I have advanced two suppositions,
_neither of which is grounded on facts_: Now, with regard to the one, he
has acknowledged, that the mouldering of stones takes place, which is
the fact on which that proposition is grounded; and with regard to the
other, the only authority given against it is founded expressly upon
the moving of soil by means of the rain water, in order to make sloping
plains of mountains. Here, therefore, I have grounded my propositions
upon facts; and our author has founded his objections, first, upon a
difficulty which he has himself removed; and, secondly, upon nothing but
a visionary opinion, with regard to an earth which is not yet made, and
which, when once made, is never more to change.

After making some unimportant observations,--of all water not flowing
into the sea,--and of the travelled materials being also deposited upon
the plains, etc. our author thus proceeds: "Hence the conclusion of