"Value of Scientific Knowledge. -In the practice of any intelligent occupation or art, in so far as the practice attains to perfection, there are manifested in the processes certain scientific principles and methods to which the work of the one practising the art conforms. In the successful practice, for example, of the art of composition, there are manifested the principles of rhetoric; in that of housebuilding, the principles of architecture; and in that of government, the principles of civil polity. In practising any such art, moreover, the worker finds that a knowledge of these scientific principles and methods will guide him in the correct practice of the art, -a knowledge of the science of rhetoric assisting in the art of composition; of the science of architecture, in the art of housebuilding; and of the science of civil polity, in the art of government. "