Seeing and knowing revisited

Both Cunliffe and the LSJ include both εἶδον (aorist, “saw”) and οἶδα (perfect, “know”) under the same rubric, which can be very misleading to intermediate students of Greek: yes, etymologically the Greek verb for “to know” at some point meant “to be in an enduring state that results from having seen,” but as a matter of actual usage it’s best to treat them as separate verbs.

Thus:

1. The present forms never appear. The fake present form *εἴδω which Cunliffe and the LSJ use as a citation form is posited in order to explain a first aorist ἐεισάμην (on which see below)

2. The second aorist εἶδον always means “see.” (Or sometimes, in the middle, “seem.”) Its unaugmented stem is ἰδ-. Both in Attic and in Homer, the other tenses of “to see” are supplied by ὁράω.

3. The first aorist ἐεισάμην is only used in the middle (i.e., it is a middle deponent), and means “seem” — compare Latin videor.

4. The perfect οἶδα always means “know,” and is used as a present; there are likewise future perfect forms that are used in a future sense, and pluperfect forms used in a imperfect sense. Sometimes dictionaries will shortcut the confusing morphology by simply calling these forms “future” and “imperfect.” Its morphology is very irregular; the most common stem is εἰδ-, but ἰδ- and οἰδ- also occur. (Under the influence of certain consonants, δ may become σ in any of these stems.)

If it’s helpful for you to think of this as οἶδα lending its aorist to ὁράω, by all means do so.

A note on the most glaring ambiguity:

εἴδομεν, εἴδετε are either the indicative of εἶδον, or (in Homer) the short-vowel subjunctive of οἶδα. The subjunctive of εἶδον is ἰδωμεν, ἰδητε: long-vowel (because the second aorist is thematic) and derived from the unaugmented stem.