First and Second Conjugations
So far all the verbs we have seen belong to the third conjugation. The first and second conjugations function somewhat differently.
To a large extent one simply has to memorize these different forms. However, there are some tips that can reduce the burden of memorization. In the present and future the first and second conjugations take largely the same endings as each other, except that the second conjugation has a stem vowel e where the first conjugation has a: first conjugation -ō, -ās, -at, -āmus, -ātis, -ant and -ābō, -ābis, -ābit, -ābimus, -ābitis, -ābunt versus second conjugation -eō, -ēs, -et, -ēmus, -ētis, -ent and -ēbō, -ēbis, -ēbit, -ēbimus, -ēbitis, -ēbunt. In the perfect the endings are exactly the same in all three conjugations (as well as in the irregular verb sum): -ī, -istī, -it, -imus, -istis, -ērunt. Thus in the perfect the three conjugations are not useful categories; in order to know how to conjugate a verb in the perfect one simply needs to find the perfect stem from its principal parts. The principal parts of these verbs are as follows:
First conjugation paradigm verb: amō, amāre, amāvī, amātum ‘love’ Second conjugation paradigm verb: moneō, monēre, monuī, monitum ‘advise’, ‘warn’ Third conjugation paradigm verb: regō, regere, rēxī, rēctum ‘rule’
These principal parts also illustrate how to identify which conjugation a verb belongs to: the second principal part ends in -āre for first-conjugation verbs, in -ēre for second-conjugation verbs, and in -ere with a short e for third-conjugation verbs. (Notice the partial correlation between the middle vowel of each infinitive and the stem vowel of that conjugation, which is -ā- or -a- in the first conjugation, -ē- or -e- in the second conjugation, and -i- in the third conjugation.) It is therefore very important to learn the quantity of the e of the second principal part when memorizing principal parts. The second principal part can also be used as a key to forming the present and future: take the second principal part, drop the last three letters, and add the endings that in these paradigms follow the am-, mon-, and reg-.