[*] 169. The tenses of the Perfect System in the active voice are made from the Perfect Stem as follows:— [*] a. In the Perfect Indicative the endings -ī, -istī, etc. are added directly to the perfect stem: as, amāv-istī , tēx-istis . [*] b. In the Pluperfect Indicative the suffix -eram, -erās, etc. is added to the perfect stem: as, amāv-eram , monu-erās , tēx-erat .
[*] Note.--This seems to represent an older †-is-ām etc. formed on the analogy of the Future Perfect in -erō (older †-is-ō: see c below) and influenced by eram (imperfect of sum ) in comparison with erō (future of sum ).[*] c. In the Future Perfect the suffix -erō, -eris, etc. is added to the perfect stem: as, amāv-erō , monu-eris , tēx-erit .
[*] Note.--This formation was originally a subjunctive of the s-aorist, ending probably in †-is-ō. The -is- is doubtless the same as that seen in the second person singular of the perfect indicative ( vīd-is-tī ), in the perfect infinitive ( vīd-is-se ), and in the pluperfect subjunctive ( vīd-is-sem ), s being the aorist sign and i probably an old stem vowel.[*] d. In the Perfect Subjunctive the suffix -erim, -eris, etc. is added to the perfect stem: as, amāv-erim , monu-eris , tēx-erit .
[*] Note.--This formation was originally an optative of the s-aorist (-er- for older -is-, as in the future perfect, see c above). The i after r is the optative mood-sign ī shortened (see § 168. e. N.2). Forms in -īs, -īt, -īmus, -ītis, are sometimes found. The shortening in -ĭs, -ĭmus, -ĭtis, is due to confusion with the future perfect.[*] e. In the Pluperfect Subjunctive the suffix -issem, -issēs, etc. is added to the perfect stem: as, amāv-issem , monu-issēs , tēx-isset .
[*] Note.--Apparently this tense was formed on the analogy of the pluperfect indicative in †-is-ām (later -er-am, see b), and influenced by essem (earlier † essēm ) in its relation to eram (earlier † esām ).1