Lotze, H. (1885). Of the train of ideas (E. Hamilton & E. E. C. Jones, Trans.). In H. Lotze & E. Hamilton, E. E. C. Jones (Trans.), Microcosmus: An essay concerning man and his relation to the world (pp. 193-219). Edinburgh, Great Britain: T & T Clark.
http://dx.doi.org/10.1037/14112-009
Through the mechanism of association a number of possible paths are opened to the train of thought into which it can strike, and between which it must choose. Now, as each of the ideas present is trying to bring back all the others with which throughout life it has successively been bound up, the decision as to what, out of all this abundance, is at any moment first to return to consciousness, will depend on a convergence of different conditions. The greater the number of resembling points common to a forgotten idea with the one now in the ascendant, the more easily will it be revived by the latter, for the more numerous are the single threads forming the bond that unites them. At the same time, however, their efficacious affinity will not consist solely in their resemblance as to content; even without such agreement,an idea may, in many indirect ways, be more or less closely connected with the purport of a train of thought now going on, with which previous reflection has associated it as an essential related point, as a constituent, as an example, or as a concomitant. Nay, an indefinite mood of feeling will make two groups of ideas to which its presence lent a common colouring, appear, in spite of difference of content, more akin to each other than to others more of the same stamp. In the place of an abiding contrast between ideas, decisive of the force with which they repel or revive one another, we have therefore to put a degree of affinity determined anew each moment, and altering, as does the contrast of two colours with a change in their background. No less fluctuating is the other condition determining the direction of the train of thought, the degree of interest pertaining to each idea, which constitutes the strength with which it seeks to make itself prominent in consciousness. No subsequent moment brings back the same total sum of ideas, feelings, and efforts, and the same state of body, in connection with which the impression formerly reached its maximum of interest. It accordingly contributes to determine the further course of thought, not at its old rate, but at the newly-fixed value to which it was able to rise, after it had entered, with that which it had before,into this new conflict with new relations. Under these conditions a train of ideas developes into the fluctuating and changeful scene with which we are all familiar, and whose apparently wanton play often fills us with amazement, because we never can catch sight of its moving springs. For the complete reason for the character of each future moment lies exclusively in the total condition of our soul during the present one, but of this state self-scrutiny never shows us more than a few fragments; we do indeed become aware of the order of sequence of our past ideas, but we are never in a position to analyze at once the peculiarities of our bodily state, of our frame of mind, of our volitions, and lastly, of the special mutual relations into which all these elements are woven together. And yet even the least and most trivial item of our train of ideas depends on nothing else than the sum of all these conditions taken together; for it does not take place in an otherwise empty consciousness, but in the whole full living soul, that is always active at the same time in those different directions, and cannot be active again in this special way without—thanks to the unity of its being—having those also recalled in its process of thought. (PsycINFO Database Record (c) 2016 APA, all rights reserved)