It was indeed wonderful to observe how a man who could study these dry details with such patience, and even with pleasure, could pass at once into the fields of political science and compel a wholly different class of facts to yield to him the loftiest generalizations. But in truth the process was the same in both instances. It was the original investigation of facts for the purpose of framing a just theory. It is a common practice, even with able men, to disparage the conclusions founded upon the employment of the reasoning powers as being _mere theory_; as if their own conclusions, so far as they have any value, were reached in any other way. These are the criticisms of men who are too indolent to engage in the work of patient investigation, or not sufficiently instructed in the methods by which it should be pursued. Undoubtedly there are many minds that undertake the task of evolving the laws underlying some subject matter and reach conclusions which are confidently believed and asserted to be true, but that turn out when adopted in practice to be erroneous. It is in this way that the results of investigation and reasoning are brought into discredit. But the fault in such cases is not that the conclusions are those of mere theory, but of erroneous theory. The reasoner lacks the patience, or the skill, to embrace in his investigation all the material facts, and to exclude all others. These are, indeed, the rarest of qualities. They are possessed in an eminent degree by a few men only in each generation, and the value of such men to society is inestimable. Governor Tilden's pre-eminence was especially manifest here. His educated intelligence was able to pronounce, as if by instinct, whether the conclusion he had reached was sufficiently certain to be made the basis of action, or was so encumbered with doubt as to call for further scrutiny into the facts. He knew how--to use his own happy phrase--"to limit theory by practice and enlighten practice by theory."