157: From Wicksteed, The Common Sense of Political Economy, Book I, Chapter 3:
In the first place we must know what we want, and must distinguish the presence of things themselves from a mere assurance or conventional indication that they are there. There are people who seem hardly to reckon with any direct perceptions or experiences of their own at all. They regulate their lives, and apparently even their feelings, by symbols and indices rather than facts. They are like the Professor who compared his map with the contour of the coast-line, and then declared himself satisfied as to the "perfect correctness"—of the coast-line. They cannot tell you whether they are feeling well, or whether they are in good spirits, unless they know whether the house in which the question is asked is built on clay or gravel, and how many feet it is above the level of the sea. They do not even eat what they like or what suits them, but things that have become to them symbols of festivity, languor, or of vigour, as the case may be. The extreme and all-embracing power of this disease specially besets men who pique themselves on their practical views of life, their robust common sense, and their preference for solid facts above mere phantoms. For money, as we shall see,*14 can never be more than the means (though it may be the necessary means) to happiness, and the man who habitually thinks of things under their pecuniary aspects becomes the slave to a symbol and will often sacrifice the thing symbolised to it.