First of all, the first element must be etymologically perfectly clear; cf. kingdom, bishopric as against nos-tril, gos-sip.

Secondly, the second element must not occur in one or two combinations only, but in a sufficiently large group of words, in all of which it modifies the meaning of the first member in the same way; cf. nos-tril, gos-sip, as against ‘kingdom,’ ‘widowhood.’

This second condition can scarcely be fulfilled except in cases where—

Thirdly, the second element has originally, or in its combination with the others, some such abstract and general meaning as state, condition, quality, action, etc.

A few words on one of the best-known suffixes in English will make this clear. Though the phrase would hardly stand in written or literary language, we might indicate a dealer in pianos as the piano-man, i.e. ‘the man who has pianos.’ In the oldest stages of language, not only could a single noun be thus used with an almost adjectival force, but even a compound (or what was then still a syntactical co-ordination) of two or more nouns, or of adjective and noun, could be thus employed. Thus, e.g., in Sanscrit, a much-rice-king, would mean ‘a king who possesses much rice,’ i.e. ‘is rich;’ and the group man-shape (or its equivalent) might have been used for man-shape-having. Such compounds abound in Sanscrit, and could be formed at will. They were called Bahuvrîhi compounds. Now, without of course wishing to assert that the very combination man-ly is an original one, it is to such a combination of a noun with the noun which afterwards became lic in Anglo-Saxon that we owe the suffix ly. The phonetic differentiation and the development of meaning from shape-having to appearance or quality-having, isolated the member from its corresponding independent form (which in German and Dutch still exists as Leiche and Lyk = body or corpse), and gave us lic (later ly) as a suffix.

From all that we have said it must be clear that this process has gone on neither in prehistoric nor in historic times only, but is one which is repeated again and again, and consequently—seeing that prehistoric times are of unknown, but certainly enormous length—we must be on our guard against assuming that all these prototypes of Indo-Germanic suffixes must necessarily have existed at one time as independent words in the language, before the process which transformed them into suffixes began to operate. We may, nay, we are almost compelled to assume that there, too, they arose in succession, and that then as now, whenever phonetic decay or other causes had affected a suffix to such an extent as to take away the appearance of a derivative from what was once a compound, the suffix was no longer felt as such; it ceased to serve for new combinations, and another more weighty suffix took its function and supplanted it in all but a few remaining cases.

The most superficial knowledge of any modern language, or of Latin etymology, is sufficient to show that it is as impossible to draw a line between suffix and flectional termination, as between syntactical group and compound. Even a Frenchman, unless he has had the true historical explanation pointed out to him, feels in a future tense like j’aimerai, a verb-stem aim, and a termination -erai indicative of futurity, though, nowadays, there are but few students of French grammar who ignore the fact that aimerai is a compound of the infinitive aimer and the first person singular, present, indicative, ai = (I) have. Similarly, we may safely assume that few Romans felt in a pluperfect amaveram a perfect stem amav and eram the imperfect of sum, much less in amabo a present stem ama and a suffix derived from the same root as their perfect fu-i. It is certainly useless to illustrate this further.

We may now conclude with three observations, the truth of which will be apparent from what has gone before.

First. Even when an inflected form, by means of comparative study of all its oldest forms and equivalents in cognate languages, has been brought back to its prototype, and analysed into what are commonly considered to be its component parts, we must remember that these parts cannot have been fused into the integer which we now find made up of them, and yet have retained their original form and original meaning. Just as kingdoms has certainly not arisen from king + dom + s, a Greek optative pherois is not a compound of pher + o + i + s, though, undoubtedly, each of these elements have their regular representatives in other words of the same function, and most probably had their prototypes in fuller forms, in a more independent state. We have no means of knowing what these forms were, or what their original function was when still independent.

Second. Many words which we now consider as “simple” may have been compound or derivative. Our inability to further analyse does not prove primitive unity.