7.  Sometimes perspicuity demands that the ordinary principles of Sequence be abandoned altogether.  Thus: 

  a) We may have the Present or Perfect Subjunctive after an historical
  tense; as,—­

    Verres Siciliam ita perdidit ut ea restitui non possit, Verres so
    ruined Sicily that it cannot be restored (Direct statement:  non potest
    restitui);

ardebat Hortensius dicendi cupiditate sic, ut in nullo flagrantius studium viderim, Hortensius burned so with eagerness to speak that I have seen in no one a greater desire (Direct statement:  in nullo vidi, I have seen in no one).

NOTE.—­This usage is different from that cited under 6.  Here, by neglect of Sequence, the Perfect is used, though a principal tense; there the Perfect was used as an historical tense.

  b) We may have a principal tense followed by the Perfect Subjunctive used
  historically; as,—­

    nescio quid causae fuerit cur nullas ad me litteras dares, I do not
    know what reason there was why you did not send me a letter.

  Here fuerit is historical, as is shown by the following Imperfect
  Subjunctive.

Method of Expressing Future Time in the Subjunctive.

269.  The Future and Future Perfect, which are lacking to the Latin Subjunctive, are supplied in subordinate clauses as follows:—­

1. a) The Future is supplied by the Present after principal tenses, by the
  Imperfect after historical tenses.

  b) The Future Perfect is supplied by the Perfect after principal tenses,
  by the Pluperfect after historical tenses.

  This is especially frequent when the context clearly shows, by the
  presence of a future tense in the main clause, that the reference is to
  future time.  Thus:—­

    Galli pollicentur se facturos, quae Caesar imperet, the Gauls promise
    they will do what Caesar shall order;

    Galli pollicebantur se facturos, quae Caesar imperaret, the Gauls
    promised they would do what Caesar should order;

    Galli pollicentur se facturos quae Caesar imperaverit, the Gauls
    promise they will do what Caesar shall have ordered;

    Galli pollicebantur se facturos quae Caesar imperavisset, the Gauls
    promised they would do what Caesar should have ordered.

2.  Even where the context does not contain a Future tense in the main clause, Future time is often expressed in the subordinate clauses by the Present and Imperfect Subjunctive.  Thus:—­

    timeo ne veniat, I am afraid he will come;

    Caesar exspectabat quid consili hostes caperent, Caesar was waiting to
    see what plan the enemy would adopt.

3.  Where greater definiteness is necessary, the periphrastic forms in -urus sim and -urus essem are employed, especially in clauses of Result, Indirect Questions, and after non dubito quin; as,—­