Ch. I.] ITS OBJECTS, AND PLAN. 3 into the merits of the question on an open and fair field. By tlius freely disclosing to my opponents the plan of attack in tended to be followed in the approaching discussion, my chance of success is certainly not augmented : but truth, not victory, is the object contemplated; and if my conclusions have been legitimately deduced from the facts brought for ward, their value cannot be diminished by an exposure to the fullest scrutiny. It may possibly be regarded as a mark of great presump tion, in thus venturing to attack opinions which are advocated by the highest authorities: and it can only be urged in ex tenuation of such a prepossession against my labours, that geology is as yet in its infancy ; and that its pursuit does not, like astronomy, and the more perfect mathematical sciences, require a great depth of learning and acumen in order to enable a zealous disciple to promote its advancement. Appealing, therefore, to my long, and I trust not altogether unprofitable, examination of the primary rocks, I rely on the well known candour and liberality of the eminent men from whom I have presumed to differ; feeling convinced that, if I should substantiate any objection to their theory, they will rejoice that an error has been corrected. In conducting the proposed enquiry, there are two objects which will demand attention: — First, the description of the primary rocks both of Cornwall and of other countries, in order to ascertain in what respects they are analogous to each other; and, in the next place, an examination whether the phenomena exhibited by these rocks are in accordance with the principles of the prevailing theory. On this plan, the following pages will be nearly equally divided between a narration of facts and hypothetical specu lations : — and the former part will lead to such lengthened preliminary details, as to constitute an essay on primary geology; which, so far from detracting from the interest of the work, may, perhaps, impart to it a more permanent value b 2