We must guard, however, against entertaining the supposition that a Unitary Science will bring _all_ the Phenomena of the universe within the compass of _Demonstrable_ apprehension. The province of Science is not infinite, but circumscribed. We are limited in the application of Mathematical Laws, even within the sphere of Pure Mathematics; general equations of the fifth degree having until recently resisted all attempts to solve them; and fields yet remain into which we cannot advance. The power of the human mind to analyze Phenomena ceases at some point, and there our ability to _apply_ Scientific Principles, however indubitable in themselves, ends. It is the office of Exact Science to furnish us with a knowledge of the inherent Laws which everywhere pervade the Universe and govern continuously and unalterably its activities. To the extent to which it is possible to trace the constituent elements of Thought or Things we can have the guidance of these Laws or Principles. But when we reach that point in any department of investigation where the complexity of the Phenomena renders it impossible for the human intellect to successfully analyze it and discover its separate parts, the sphere of accurate Scientific Knowledge is transcended. The Intuition--the faculty which apprehends what we may call the spirit of _Concrete_ things, which goes to conclusions by a rapid process that overleaps intermediate steps, which is our guide in the numerous decisions that we are called to make in our every-day life, and which perceives, in a somewhat vague and indefinite manner--becomes our only guide in this Realm of the Inexact. The advent of a Unitary Science and the inauguration of a true Deductive Method in all domains of Thought, will, indeed, completely revolutionize our Scientific bases, and render precision and infallibility possible in domains where now only conjecture and probability exist. It will enable us to establish on a firm and secure foundation the _Laws or Principles of every department of the Universe of Matter and of Mind_, and to penetrate the Phenomena of all realms to an extent now scarcely imagined. It will furnish us the 'Criterion of Truth' so long sought after--a ground of intellectual agreement in all the concerns of life, so far as this is essential, similar to that which we now have in Mathematics, where difference of opinion is impossible because _proof is of a nature to be alike convincing to all_.