r appearance of presumption than any attempt at reasoning
respecting the purposes of the Divine Being; and that in many cases
it would be thought more consistent with the modesty of humanity to
limit its endeavor to the ascertaining of physical causes than to
form conjectures respecting Divine intentions. But I believe this
feeling to be false and dangerous. Wisdom can only be demonstrated
in its ends, and goodness only perceived in its motives. He who in a
morbid modesty supposes that he is incapable of apprehending any of
the purposes of God, renders himself also incapable of witnessing
his wisdom; and he who supposes that favors may be bestowed without
intention, will soon learn to receive them without gratitude.

[43] See Appendix 2. Slaty Cleavage.

[44] As we had to complain of Dante for not enough noticing the
colors of rocks in wild nature, let us do him the justice to refer
to his noble symbolic use of their colors when seen in the hewn
block.

"The lowest stair was marble white, so smooth
And polished that therein my mirrored form
Distinct I saw. The next of hue more dark
Than sablest grain, a rough and singed block,
Cracked lengthwise and across. The third, that lay
Massy above, seemed porphyry, that flamed
Red as the life-blood spouting from a vein."

This stair is at the gate of Purgatory. The white step means
sincerity of conscience; the black, contrition; the purple (I
believe), pardon by the Atonement.

CHAPTER IX.

OF THE MATERIALS OF MOUNTAINS:--SECONDLY, SLATY CRYSTALLINES.

Sec. 1. It will be remembered that we said in the last chapter (Sec. 4) that
one of the notable characters of the whole group of the crystallines was
the incomprehensibility of the processes which have brought them to
their actual state. This however is more peculiarly true of the slaty
crystallines. It is perfectly possible, by many processes of chemistry,
to produce masses of irregular crystals which, though not of the
substance of granite, are very like it in their mode of arrangement.
But, as far as I am aware, it is impossible to produce artificially
anything resembling the structure of the slaty crystallines. And the
more I have examined the rocks themselves, the more I have felt at once
the difficulty of explaining the method of their formation, and the
growing interest of inquiries respecting