Now for the illustration! Suppose that, as I am writing this paragraph, it occurs to me to look up a reference, for quotation, in a particular book that stands on the shelf by my side. I turn toward the shelf, recognise the book, take it in my hand and turn the pages, and presently find the passage I had in mind to use. I have performed _an impulsive action_, in the sense of our definition; the illustration is complete. I shall go on to put a marker in the book, or to copy out the sentence, and ultimately I shall return the book to the shelf; but these later developments do not here concern us. Let us try to analyse this action; and since the mental accompaniment is fairly complex, let us analyse, at first, only in large and gross terms. We begin with a preparatory phase, in which there are two things to notice: the _intention to move_ (it occurs to me to look up the reference) and the _idea of the result_ of movement (finding the required passage for quotation). Then follows a middle phase, in which the outstanding thing is the _perception of the object_ of movement (I see and identify the book on the shelf). The final phase includes a _perception of movement_ itself in kinæsthetic terms (I reach out, take the book down, turn the pages) and also the _perception of the result_ of movement (I find the sentence). So we have three roughly distinguishable phases, each one issuing from that which preceded it, which we may formulate as follows: Intention of movement } → Perception { Perception of movement Idea of result } of object → { Perception of result. You understand that the arrows indicate a definite direction; the second and third phases issue from the first; _the whole course is predetermined_. When I perceive the book, under this impulsive determination, the associative tendencies have no freedom of play; I cannot think that the back is breaking, or that I know the writer, or that the chalky paper is detestable, though all of these are things that might occur to me at another time; I can only recognise the book as the book that will realise my idea of result, that contains the passage I need. The whole course, again, is singly, _unequivocally_, predetermined; it occurs to me to use the quotation, and I do not reflect or hesitate; I act directly and forthright upon the suggestion; there is no conflict. In a word, the example shows us action in its simplest form and with a maximum of mental concomitant; and that is what we agreed to regard, from the psychological point of view, as a typical action. Analysis of this crude kind does no more than give us our bearings. If we are to lay out the facts with scientific accuracy, we must carry actions into the laboratory, and examine them under experimental conditions. We do this by way of the ‘reaction experiment.’