In this brief chapter we cannot attempt to go into details, and in speaking of the morphology of vulgar Latin we must content ourselves with sketching its general characteristics and tendencies, as we have done in the case of its phonology.  In English our inflectional forms have been reduced to a minimum, and consequently there is little scope for differences in this respect between the written and spoken languages.  From the analogy of other forms the illiterate man occasionally says:  “I swum,” or, “I clumb,” or “he don’t,” but there is little chance of making a mistake.  However, with three genders, five declensions for nouns, a fixed method of comparison for adjectives and adverbs, an elaborate system of pronouns, with active and deponent, regular and irregular verbs, four conjugations, and a complex synthetical method of forming the moods and tenses, the pitfalls for the unwary Roman were without number, as the present-day student of Latin can testify to his sorrow.  That the man in the street, who had no newspaper to standardize his Latin, and little chance to learn it in school, did not make more mistakes is surprising.  In a way many of the errors which he did make were historically not errors at all.  This fact will readily appear from an illustration or two.  In our survey of preliterary Latin we had occasion to notice that one of its characteristics was a lack of fixity in the use of forms or constructions.  In the third century before our era, a Roman could say audibo or audiam, contemplor or contemplo, senatus consultum or senati consultum.  Thanks to the efforts of the scientific grammarian, and to the systematizing influence which Greek exerted upon literary Latin, most verbs were made deponent or active once for all, a given noun was permanently assigned to a particular declension, a verb to one conjugation, and the slight tendency which the language had to the analytical method of forming the moods and tenses was summarily checked.  Of course the common people tried to imitate their betters in all these matters, but the old variable usages persisted to some extent, and the average man failed to grasp the niceties of the new grammar at many points.  His failures were especially noticeable where the accepted literary form did not seem to follow the principles of analogy.  When these principles are involved, the common people are sticklers for consistency.  The educated man conjugates:  “I don’t,” “you don’t,” “he doesn’t,” “we don’t,” “they don’t”; but the anomalous form “he doesn’t” has to give way in the speech of the average man to “he don’t.”  To take only one illustration in Latin of the effect of the same influence, the present infinitive active of almost all verbs ends in -re, e.g., amare, monere, and regere.  Consequently the irregular infinitive of the verb “to be able,” posse, could not stand its ground, and ultimately became potere in vulgar Latin.  In one respect in the inflectional forms of the verb, the purist was unexpectedly successful.  In comedy of the third and second centuries B.C., we find sporadic evidence of a tendency to use auxiliary verbs in forming certain tenses, as we do in English when we say:  “I will go,” “I have gone,” or “I had gone.”  This movement was thoroughly stamped out for the time, and does not reappear until comparatively late.