Short-cut to the Optative: 

1) Essential meaning : 'Mood' of wish or 'less vivid' supposing=may/might...

a) as a Main verb (with εἴθε or εἰ γάρ)

expresses a Wish or prayer, 'would that... (might happen)'

b) in dependent clauses after past tense main verb; esp. subjuntive --> optative.

2) Formed as follows: (open handy chart in new window)

a) no augment; present or aorist stem (or future) + ι or ιη + 2nd aor. endings

So 'may we receive' is λαμβανο-ι-μεν ...λαβο-ι-μεν

Except, -οιν--> -οιμι or οιεν ... So 'may I receive' is λαβο-ι-μι.

'May they receive' is λαβο-ι-εν

[-εν is the proper 'they' ending for all actives and aor.passive)

1st aor. -σαιν --> σαιμι ...-σαιεν (or -σειαν]

So 'may I write' (aor.) = γραψα-ι-μι

b) for thematic verb forms the connecting vowel is -o-

c) for any vowel-stem verb (thematic or athematic)

the sign of the optative is -ιη- in the singular only

So 'might I honor' = τιμα-ο-ιη-ν-->τιμῳην (thematic)

'Might I stand' =ἱστα-ιη-ν-->ἱσταίην (athematic)

φιλε-ο-ιη-ν-->φιλοίην

τιθε-ιη-ν --> τιθείην

δηλο-ο-ιη-ν--> δηλοίην (thematic)

διδο-ιη-ν--> διδοίην (athematic)

All aorist passives (athematic) = -θ]ε-ιη-ν

plurals, -θ]ε-ι-μενͺ κτλ.