particulars may seem, the application of the general law to them admits only of _probability_, which may, indeed, as the induction has been wider, and the circumstances of observed analogy more numerous, approach more or less to certainty, but must always be short of it, even in its nearest approximation. * * * * * Such, then, is _physical inquiry_, both as to its objects, and its mode of procedure, particularly as it regards the universe without; and the laws which regulate our inquiry in the internal world of thought are, in every respect, similar. The same great objects are to be had in view, and no other,--the analysis of what is complex, and the observation and arrangement of the sequences of phenomena, as respectively antecedent and consequent. In this respect, also, I may remark, the philosophy of matter and the philosophy of mind completely agree--that, in both equally, our knowledge is confined to the phenomena which they exhibit. We give the name of _matter_ to the unknown cause of various feelings, which, by the constitution of our nature, it is impossible for us not to refer to something external as their cause. What it is, independent of our perception, we know not; but as the subject of our perception, we regard it as that which is extended, and consequently divisible, impenetrable, mobile; and these qualities, or whatever other qualities we may think necessary to include for expressing the particular substances that affect our senses variously, constitute our whole definition of matter, because, in truth, they constitute our whole knowledge of it. To suppose us to know what it is in itself, in absolute independence of our perception, would be manifestly absurd: since it is only by our perception,--that is to say, by the feelings of our mind,--that it can be known to us at all; and these mere feelings of the mind must depend, at least, as much on the laws of the mind affected, as on the laws of the substance that affects it. Whatever knowledge we may acquire of it, therefore, is relative only, and must be relative in all circumstances; though, instead of the few senses which connect us with it at present, we were endowed with as many senses as there are, perhaps, qualities of matter, the nature of which we are at present incapable of distinguishing;--the only effect of such increased number of senses being, to render more qualities of matter known to us, not to make matter known to us in its very essence, as it exists without relation to mind.