instead of accepting the qualities and values the ends and forms of this world as providing the objects of knowledge, subject to their being given acertain logical arrangement, experimental inquiry treats them as of- fering achallenge to thought. They are the materials of problems not of solutions. They are to be known, rather than objects of knowledge. The first step in knowing is to locate the problems which need solution. This step is per- formed by altering obvious and given qualities. These are effects} they are things to be understood, and they are under- stood in terms of their generation. The search for "efficient causes" instead of for final causes,