But to see how necessary it is to judge in this manner, not partially, but upon the whole, we may observe, that there are two ways by which the visible materials or distinguishable bodies of a former earth, not only _may_ be rendered invisible in the composition of our present earth, but _must_ be so upon many occasions. These are, _first_, by mechanical comminution, which necessarily happens, more or less, in that operation by which bodies are moved against one another, and thus transported from the land to the bottom of the deepest seas; _secondly_, by chemical operations, (whatever these may be, whether the action of water or of fire, or both), which are also necessarily employed for consolidating those loose materials, that are to form the rocks and stones of this earth, and by means of which those materials are to have their distinguishable shapes affected in all degrees and obliterated. Therefore, to demand the visible appearance of those materials in every stratum of the earth, or in every part of a stratum, is no other than to misunderstand the subject altogether. The geological observations, which have been thus alleged as contradicting my theory, are stratified bodies, containing proofs of the general origin which I attribute to the earth, but proofs which may not always be seen with equal facility as those which even convince the vulgar. Our author has surely perplexed himself with what writers of late have said concerning primitive mountains as they are called, a subject of deeper search, than is commonly imagined, as I hope to show in the course of this work. It is an interesting subject of investigation, as giving us the actual view of those operations of nature which, in forming my Theory of the Earth, more general principles had led me to conclude _might be_. But, it is a subject which, I am afraid, will lead me to give farther offence to our author, however innocent I may be in giving nothing but what I have from nature.