H/E was the son of a merchant in Edinburgh, was born June 3, 1726, studied first in his native city, then in Leyden, where he took the degree of M.D., and devoted his life to agricultural pursuits and scientific investigations in chemistry, mineralogy, and specially in geology.He died March 26, 1797.He is best known as the author of a " Theory of the Earth," which was expounded in a clear and elegant manner by Playfair.He accounts for the present condition of the earth by the operation of a central heat; and there was long a contest between his theory and that of Werner, {262}
who explains the formation of strata by water; geologists now find place for both agencies.It is not so generally known that he found much satisfaction in the pursuit of metaphysics, and is author of an elaborate work in three large quarto volumes, " An Investigation of the Principles of Knowledge, and of the Progress of Reason from Sense to Science and Philosophy." The work is full of awkwardly constructed sentences and of repetitions, and it is a weariness in the extreme to read it.Yet we are made to feel at times that these thoughts must be profound, if only we could understand them.He certainly speculates on recondite subjects, but does not throw much light on them.Knowledge is considered as consisting first of external information;secondly, of internal conception.In the first, mind is made to know no passion; in the second, it is made to known action." "Knowledge is no more the attribute of mind than mind is that of knowledge.We suppose that there is a substance called mind, and we then attribute knowledge to this substance; but knowledge is the very thing which in this case subsists.Space and time are conceptions of the mind, founded upon activity and inactivity; that is to say, upon the volition of the mind, whereby either on the one hand action is produced that is change, or on the other hand inaction is ordained wherein the powers of the mind are preserved in a state of attention to the idea then in view."In his view of matter, he expounds a dynamical theory which becomes an ideal theory, closely approaching that of Berkeley."There is no inert matter subsisting with magnitude and figure; but the external thing exists with moving and resisting powers." " Real solidity or impenetrability is truly a conception of our intellect, like that of equal lines and angles, but it is a supposition which nothing in nature authorizes us to make." " We deceive ourselves when we imagine that there is a subsisting independent of our thought, -- an external thing, which is actually extended and necessarily figured." " Figure is a thing formed in the mind alone, or produced by the proper action of our thinking substance." He says it is wrong to suppose that magnitude and figure subsist without our mind.
He tells us that big theory agrees with that of Berkeley in this, that " figure and magnitude are not real and absolute qualities in external things; " but he holds that " there is truly an external existence as the cause of our knowledge,"whereas Berkeley holds that there is no such external existence.We have here a view of matter very different from that of the Scottish school, who have commonly been inclined to the doctrine of Descartes.Metaphysical science will now have to set itself to determine what substantial truth there is in idealism, and, with the light of modern inquiries as to atoms, what truth there is in the dynamical theory of matter.{263}