[§ 326]. The explanation of some fresh terms will lead us towards the definition of the word irregular.

Vital and obsolete processes.—The word moved is formed from move, by the addition of -d. The addition of -d is the process by which the present form is rendered præterite. The word fell is formed from fall, by changing a into e. The change of vowel is the process by which the present form is rendered præterite. Of the two processes the result is the same. In what respect do they differ?

For the sake of illustration, let a new word be introduced into the language. Let a præterite tense of it be formed. This præterite would be formed, not by changing the vowel, but by adding -d. No new verb ever takes a strong præterite. The like takes place with nouns. No new substantive would form its plural, like oxen or geese, by adding -en, or by changing the vowel. It would rather, like fathers and horses, add the lene sibilant.

Now, the processes that change fall, ox and goose into fell, oxen, and geese, inasmuch as they cease to operate on the language in its present stage, are obsolete processes; whilst those that change move into moved, and horse into horses, operating on the language in its present stage, are vital processes.

A definition of the word irregular might be so framed as to include all words whose forms could not be accounted for by the vital processes. Such a definition would make all the strong verbs irregular.

The very fact of so natural a class as that of the strong

verbs being reduced to the condition of irregulars, invalidates such a definition as this.

[§ 327]. Processes of necessity as opposed to processes of habit.—The combinations -pd, -fd, -kd, -sd, and some others, are unpronounceable. Hence words like step, quaff, back, kiss, &c., take after them the sound of -t; stept, quafft, &c., being their præterites, instead of stepd, quaffd. Here the change from -d to -t is a matter of necessity. It is not so with words like weep, and wept, &c. Here the change of vowel is not necessary. Weept might have been said if the habit of the language had permitted.

A definition of the word irregular might be so framed as to include all words whose natural form was modified by any euphonic process whatever. In this case stept (modified by a process of necessity), and wept (modified by a process of habit), would be equally irregular.

A less limited definition might account words regular as long as the process by which they are deflected from their natural form was a process of necessity. Those, however, which were modified by a process of habit it would class with the irregulars.