It is sufficiently indicated, in some quarters, by the mere omission of all reference to Mind or Spirit as distinct from Matter; and, in others, by elaborate attempts to explain all the phenomena of life and thought by means of physical agencies and organic laws.

The writings of Comte, Crousse, Cabanis, and Broussais,[146] afford ample evidence of its growing prevalence in France; and although it has been said by a recent historian of Philosophy that in England there has been no formal avowal, or at least no recognized school, of Materialism, since the publication of Dr.
Thomas Brown's reply to Darwin's Zooenomia, yet there is too much reason to believe that it was all along cherished by not a few private thinkers, who had imbibed the spirit of Hobbes and Priestley; and now it is beginning to speak out, in terms too unambiguous to be misunderstood, in such works as "The Purpose of Existence" and the "Letters" of Atkinson and Martineau.

But apart from the opinions of individual inquirers, it must be remembered that there is a tendency in certain studies, when exclusively pursued, to generate a frame of mind which will tempt men either to adopt the theory of Materialism, or at least to attach undue importance to physical agencies and organic laws.

This tendency may be observed in the study of Physiology, especially when it is combined with that of Phrenology and Animal Magnetism; not that there is any necessary or strictly logical connection between these studies and Materialism, for some of their ablest expounders, including Cabanis, Gall, and Spurzheim, have explicitly disavowed that theory; but simply that, in prosecuting such inquiries, the mind is insensibly led to bestow an undue, if not exclusive, attention on the phenomena and laws of our material organization, so as to become comparatively unmindful of what is mental, moral, and spiritual in the constitution of man.

For these reasons, and considering, especially, the close connection of Materialism both with the mechanical Atheism of the past, and the hylozoic Pantheism of the present age, we deem it necessary to subject its claims to a rigorous scrutiny, in connection with the subject of our present inquiry.
What, then, is the doctrine of Materialism?
What are the forms in which it has appeared, and what the ground on which it rests?
How does it stand related to the question concerning the nature and existence of God, or the constitution and destiny of Man?
A brief answer to these questions will be sufficient to show that this theory cannot be safely disregarded in any attempt to construct a comprehensive and conclusive argument on the first principles of Natural Theology.
SECTION I.
DISTINCT FORMS OF MATERIALISM.
The doctrine of Materialism has assumed several distinct phases or forms in the hands of its different advocates; and these must be carefully discriminated from each other, if we would either estimate aright their respective merits, or do justice to the parties by whom they have been severally maintained.
The grossest and most revolting form of Materialism is that which _identifies mind with matter_, and _thought with motion_.