1. Pure final clauses (expressing purpose or motive) take the
subjunctive when dependent on primary tenses, the optative when
dependent on secondary tenses. The conjunction is ἵνα, ὡς, or ὅπως.
E. g.,
τοῦτο πράττει ἵνα καλῶς ἔχῃ.
τοῦτο ἔπραττε ἵνα καλῶς ἔχοι
Bt. 590; Gl. 640; Gn. 365; H.A. 881.
2. Object clauses dependent on verbs denoting care, attention or
effort, regularly take the future indicative ὅπως, though the future
optative is possible when dependent on a secondary tense.
E. g.,
φροντίζει ὅπως καλῶς ἕξει,
ἐφρόντιζεν ὅπας καλῶς ἕζει
(or ἕζοι, see note).
Bt. 593; Gn. 1372; H.A. 885.
3. Subordinate clauses introduced by μή (trans. lest or that),
and dependent on verbs denoting fear, caution or danger, take the
subjunctive when dependent on primary tenses, the optative when
dependent on secondary tenses.
E. g.,
φοβεῖται μὴ τοῦτο πράττωμεν
ἐφοβεῖτο μὴ τοῦτο πράττοιμεν
(or πράττωμεν, see note).
Bt. 593; Gl. 610; Gn. 1378.
Note 1.—In rules 1-3, for greater vividness—as though using the
language of the person who conceived the purpose—the subjunctive
may be used even when dependent on a secondary tense (see examples
above). Gl. 638; Gn. 1372.