ON ' ASSOCIATION '-CONTEOVEESIES. 169

tions, and so on, alternating between the two lines of re- search, yet insisting on their being conducted independently. This is necessary in order that we may not fall into a circle. It is said, for example, that if we embark on the promiscuous field of mental facts, with a bad Metaphysics, that is, with wrong notions as to External Reality, Cause, Substance, and so on, all our results will be vitiated and worthless ; nevertheless, I do not see any mode of attaining a correct Metaphysics until Psychology has at least made some way upon a provisional Metaphysics, which it returns after a time to rectify and improve. (On the relations of Psy- chology to Metaphysics, see in MIND, Vol. viii., the Editor's opening article and Mr. James Ward's first article entitled " Psychological Principles ".) Psychology imperatively demands a well-defined vocabu- lary. The ultimate notions of the science must be free from ambiguity ; but to express ultimate facts with precision, and to decide what things are ultimate, constitute a laborious part of any science, most of all of mind. The process of see-saw is eminently called for here. We go on a certain way upon given definitions ; we find them open to excep- tion ; we go back and correct them, and proceed again, until some new flaws are discovered. But to stay debating ultimate questions, before making any forward movement at all, is a device that may be handed over to the Committee for arranging the debates in Pandemonium. As regards Association in particular, nothing can be more vital than a correct mode of stating and understanding the mental elements or units that enter into the associating operations. The Impression, Sensation, Presentation, Per- ception, Idea, Image, Trace, Kesiduum, Eepresentation, Memory, Recollection, must all be properly reduced to dis- tinct expression, and rendered free of ambiguity, before we know what we mean by Associative Reproduction, or Sug- gestion. The starting-point of the clearing operation evidently is to distinguish the Sensation from the Idea the state of mind under full actuality from the trace, residuum, survival and reproduction of that when the actuality has ceased : What is my precise mode of mind in surveying a fine prospect, and what is that other mode when I am remembering it ? Nor is this by any means a very simple determination. For what we choose to call sensation, presentation or actuality, is already a mixed mode, a product of associating forces. What I now see, I may have seen before, and that previous seeing combines its results with the present view. Even