It is necessary to understand that fusion of the radical element and the affix may be taken in a broader psychological sense than I have yet indicated.  If every noun plural in English were of the type of book:  books, if there were not such conflicting patterns as deer:  deer, ox:  oxen, goose:  geese to complicate the general form picture of plurality, there is little doubt that the fusion of the elements book and _-s_ into the unified word books would be felt as a little less complete than it actually is.  One reasons, or feels, unconsciously about the matter somewhat as follows:—­If the form pattern represented by the word books is identical, as far as use is concerned, with that of the word oxen, the pluralizing elements _-s_ and _-en_ cannot have quite so definite, quite so autonomous, a value as we might at first be inclined to suppose.  They are plural elements only in so far as plurality is predicated of certain selected concepts.  The words books and oxen are therefore a little other than mechanical combinations of the symbol of a thing (book, ox) and a clear symbol of plurality.  There is a slight psychological uncertainty or haze about the juncture in book-s and ox-en.  A little of the force of _-s_ and _-en_ is anticipated by, or appropriated by, the words book and ox themselves, just as the conceptual force of _-th_ in dep-th is appreciably weaker than that of _-ness_ in good-ness in spite of the functional parallelism between depth and goodness.  Where there is uncertainty about the juncture, where the affixed element cannot rightly claim to possess its full share of significance, the unity of the complete word is more strongly emphasized.  The mind must rest on something.  If it cannot linger on the constituent elements, it hastens all the more eagerly to the acceptance of the word as a whole.  A word like goodness illustrates “agglutination,” books “regular fusion,” depth “irregular fusion,” geese “symbolic fusion” or “symbolism."[106]

[Footnote 106:  The following formulae may prove useful to those that are mathematically inclined.  Agglutination:  c = a + b; regular fusion:  c = a + (b — x) + x; irregular fusion:  c = (a — x) + (b — y) + (x + y); symbolism:  c = (a — x) + x.  I do not wish to imply that there is any mystic value in the process of fusion.  It is quite likely to have developed as a purely mechanical product of phonetic forces that brought about irregularities of various sorts.]