[Footnote 346: "Lectures on Metaphysics," vol. ii. p. 26.] [Footnote 347: M'Cosh, "Intuitions," pp. 197, 198; Calderwood, "Philosophy of the Infinite," p. 24.] And now we seem to have penetrated to the centre of Hamilton's philosophy, and the vital point may be touched by one crucial question, _Upon what ultimate ground does faith itself rest?_ Hamilton says, "we believe what rests upon _authority_." But what is that authority? I. It is not the authority of Divine Revelation, because beliefs are called "instinctive," "native," "innate," "common," "catholic,"[348] all which terms seem to indicate that this "authority" lies within the sphere of the human mind; at any rate, this faith does not rest on the authority of Scripture. Neither is it the authority of Reason. "The original data of reason [the first principles of knowledge] do not rest upon the authority of reason, but _on the authority of what is beyond itself_." The question thus recurs, what is this ultimate ground beyond reason upon which faith rests? Does it rest upon any thing, or nothing? [Footnote 348: Philosophy of Sir Wm. Hamilton, pp. 68, 69.] The answer to this question is given in the so-called "Law of the Conditioned," which is thus laid down: "_All that is conceivable in thought lies between two extremes, which, as contradictory of each other, can not both be true, but of which, as mutual contradictories, one must_." For example, we conceive _space_, but we can not conceive it as absolutely bounded or infinitely unbounded. We can conceive _time_, but we can not conceive it as having an absolute commencement or an infinite non-commencement. We can conceive of _degree_, but we can not conceive it as absolutely limited or as infinitely unlimited. We can conceive of _existence_, but not as an absolute part or an infinite whole. Therefore, "the Conditioned is that which is alone conceivable or cogitable; the Unconditioned, that which is inconceivable or incogitable. The conditioned, or the thinkable, lies between two extremes or poles; and each of these extremes or poles are unconditioned, each of them inconceivable, each of them exclusive or contradictory of the other. Of these two repugnant opposites, the one is that of Unconditional or Absolute Limitation; the other that of Unconditional or Infinite Illimitation, or, more simply, the Absolute and the Infinite; the term _absolute_ expressing that which is finished or complete, the term _infinite_ that which can not be terminated or concluded."[349]