The 3rd person “s” (formerly “th”, equivalent to “t” in Latin, High German, Russian, etc.) suffix is the only remaining personal verb suffix used in English. Old English had suffixes for all 6 person-number combinations. There isn’t really a reason for its survival — just be glad we don’t have to worry about the other five grammatical persons! As far as the numbering, I believe Arabic numbers the persons in the reverse order, but in English the speaker (I / me / my) is the “first person”, the person addressed (you) is the “second person”, and everyone else (he / him / his, she / her, they / them /their, etc.) is “third person”. The subject pronouns: Singular 1st I (2nd thou) 3rd he / she / it Plural 1st we 2nd (ye) you 3rd they More good news: English only has singular and plural — most words do not have a special dual form.