A Method of Scientific investigation which proceeds from self-evident truths to necessary results by undeniable steps, would of course be preferable to one which, starting from truths whose precision and certainty might be doubtful, advances by more or less probable inferences to a more or less probable conclusion, did there not exist some powerful cause for a contrary action. A difficulty thus far insurmountable has, indeed, stood in the way of the adoption of the Deductive Method in any department of investigation, save the one already referred to. This Method, we have seen, leads to truth or error accordingly as the Principles or Laws from which it commences its reasoning process are true or false. In the Mathematics, the basic truths, being of a simple character, were arrived at by easy and instinctive mental processes, and the Method achieved in this department great success. But the other domains of human knowledge being more complex, involving more qualities or characteristics than mere Number and Form and Force, which are all that come within the scope of Mathematics, their fundamental bases or truths were not so easily attainable. Hence, when Principles or Ideas which men believed to contain all the fundamentals of a specific domain of thought were adopted as starting points of reasoning, they were generally lacking in some important element, which caused the conclusion to be in some way incorrect. We have seen the historical results of this mode of procedure in what is denominated the Anticipative or Hypothetical Method. The failure of this to secure good results, and the absence of any standard by which to be certain when a Law or Principle was fundamental, exact, and inclusive, when it was a valid basis to reason from, led to the abandonment of the Deductive Method, except in its application to Mathematics, where true starting points were known. The Observation and Classification of Facts was then resorted to, first, in a loose way, in Greece, and afterward, in a more rigorous way, in the world at large, for the purpose of endeavoring to discover, by the only mode considered effective--the examination of Phenomena--the fundamental Principles, which, like those of Mathematics, should include all the essentials of the special domain under consideration. These being discovered, might furnish, it was instinctively felt, starting points from which to work the Deductive Process, with the same success as that which attended its application to Mathematics.