[...] fusion does not [...] satisfy us as a clear indication of the inflective process. There are [...] a large number of languages that fuse radical element and affix in as complete and intricate a fashion as one could hope to find anywhere without thereby giving signs of that [...] kind of formalism that marks off such languages as Latin and Greek [...]
- Sapir (1921), a pag.130

[...] fusion of the radical element and the affix may be taken in a broader psychological sense [...]. If every noun plural in English were of the type of 'book: books', if there were not such conflicting patterns as [...] 'ox: oxen' [...] to complicate the general form picture of plurality [...] the fusion of the elements 'book' and '-s' into [...] 'books' would be felt as a little less complete than it actually is.
- Sapir (1921), a pag.131

A word like 'goodness' illustrates 'agglutination', 'books' 'regular fusion', 'depth' 'irregular fusion', 'geese' 'symbolic fusion' [...]
- Sapir (1921), a pag.132

The following formulæ 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)' [...]
- Sapir (1921), a pag.132

It does not follow that an agglutinative language may not make use of the principle of fusion, both external and psychological, or even of symbolism to a considerable extent. It is a question of tendency.
- Sapir (1921), a pag.134

[...] Greek uses the method of fusion, and this fusion has an inner psychological as well as an outer phonetic meaning. But it is not enough that the fusion operate merely in the sphere of derivational concepts [...] it must involve the syntactic relations [...]
- Sapir (1921), a pag.135

Both fusion as a general method and the expression of relational concepts in the word are necessary to the notion of 'inflection.'
- Sapir (1921), a pag.136

[...] 'fusion' and 'symbolism' may often be combined with advantage under the head of 'fusion'; even the difference between agglutination and fusion may [...] be set aside[...]
- Sapir (1921), a pag.140