In short

Greek has no separate conditional or optative endings. It builds three modal jobs out of particles you already know:

• θα + imperfect = the potential (δυνητική). This is the polite “would”: θα ήθελα “I would like”, θα μπορούσα “I could”, θα έλεγα “I’d say”. With the pluperfect (θα είχα φύγει) it means “I would have left”.
• μακάρι να / ας + subjunctive = the wish (ευχετική). The perfective subjunctive after μακάρι leaves the wish open — it may still happen; the imperfect or the pluperfect marks it as unattainable or already lost.
• φοβάμαι μη(ν) / μήπως … = the clause of fear (ενδοιαστική). The verb of fearing introduces it with μη(ν) or μήπως — ότι would report the thing as already true — and the negation inside it is the plain δεν, never a second μη.

The one thing to internalise: in Greek, pastness of form means distance from reality, not past time. θα ήθελα is about right now; μακάρι να ερχόταν is about a present that isn’t.

The rule

1. The potential: θα + παρατατικός in a main clause.

θα plus the imperfect (or the pluperfect) in an independent clause does not report the past. It softens, hedges, and makes hypothetical. Compare:

• Θα θέλω → a plain future: “I will want” (rare, and almost never what you mean).
• Θα ήθελα → “I would like” — the standard polite request in a shop, an office, a café.

The same shape gives θα μπορούσα “I could / I’d be able to”, θα προτιμούσα “I’d prefer”, θα έλεγα “I’d say”, θα ήταν καλύτερα “it would be better”. With έχω in the imperfect plus the unchanging form (φύγει, γράψει) you get the past potential: θα είχα φύγει “I would have left”. Negation is δεν, placed before θα: δεν θα ήθελα, δεν θα μπορούσα.

This lesson keeps to independent clauses. The same forms are what an αν-clause takes in its main half (αν είχα χρόνο, θα ερχόμουν) — that pairing belongs to lesson 47.

2. The wish: μακάρι να and ας.

μακάρι να (“if only”, “I hope”) is followed by a subjunctive, and the choice of form is the whole meaning:

να ήξερα! (“if only I knew!”) and ας ήταν are frozen wishes of the unattainable type — the imperfect alone carries the “but it isn’t so”.

ας is the softer, first-person-friendly particle. With the perfective it makes a proposal or a concession: ας πάμε “let’s go”, ας έρθει “let him come / fine, let him come”. Its negative is ας μην: ας μην αργήσουμε “let’s not be late”.

3. Clauses of fear: μη(ν) and μήπως.

Verbs and expressions of fearing — φοβάμαι, ανησυχώ, έχω τον φόβο, and the warning imperative πρόσεχε — take a clause introduced by μη(ν) or μήπως. Both are equally correct; μήπως is the everyday spoken choice and the safer one for a learner, because μη(ν) alone can be misread as a negative command.

• Φοβάμαι μήπως αργήσει. “I’m afraid he may be late.”
• Πρόσεχε μην πέσεις. “Careful you don’t fall.”

The crucial asymmetry: μη(ν)/μήπως is the complementiser, and it already carries the “lest” meaning. If you want to fear that something will not happen, you negate inside the clause with the ordinary δεν:

• Φοβάμαι μήπως δεν προλάβει. “I’m afraid he may not make it in time.”

Note the aspect: the feared event is a single occurrence, so the perfective subjunctive is the default (αργήσει, πέσεις, προλάβει). An ongoing state keeps the present: φοβάμαι μήπως δεν είναι καλά.

4. Final -ν on μη / μην.

μη and μην are the same word. Keep the -ν before a vowel and before κ, π, τ, γκ, μπ, ντ, τσ, τζ, ξ, ψ (μην αργήσεις, μην πεις, μην ξεχάσεις); drop it elsewhere (μη φύγεις, μη μιλάς, μη λες). Leaving it on is a much smaller sin than the mistakes below, but the rule is the same one you learned for τη(ν) and στη(ν).

Forms & patterns

The potential of θέλω: θα + imperfect. All six persons, accents shown as written.

μπορώ and προτιμώ — the two other workhorses.

The past potential: θα + υπερσυντέλικος. Only είχα inflects; φύγει never changes.

The attainable wish: μακάρι να + perfective subjunctive (έρχομαι).

The unattainable wish: μακάρι να + imperfect / pluperfect.

ας — proposal, permission, concession.

The fear clause, schematically.

That last row is the contrast worth memorising: μήπως frames the thing as feared and still open, ότι reports it as already true.

Examples

Common mistakes

• Θα θέλω ένα ποτήρι νερό. -> Θα ήθελα ένα ποτήρι νερό. — θα + present is a plain future; the polite “I would like” needs θα + imperfect.
• Θα μπορώ να σας βοηθήσω; -> Θα μπορούσα να σας βοηθήσω; — same rule: the offer is hypothetical, so the imperfect carries it.
• Μακάρι να έρχεται αύριο. -> Μακάρι να έρθει αύριο. — a single future event takes the perfective subjunctive, not the present.
• Μακάρι να είναι εδώ τώρα, αλλά είναι στην Κρήτη. -> Μακάρι να ήταν εδώ τώρα, αλλά είναι στην Κρήτη. — an impossible present wish needs the imperfect; the present would mean you still think it might be so.
• Φοβάμαι μην δεν προλάβει. -> Φοβάμαι μήπως δεν προλάβει. — μη(ν) is the complementiser and δεν is the negation; you never stack two negatives.
• Φοβάμαι ότι μην αργήσει. -> Φοβάμαι μήπως αργήσει. — ότι and μήπως are alternatives, never a pair; ότι takes the indicative of a known fact.
• Ας δεν πάμε σήμερα. -> Ας μην πάμε σήμερα. — after ας and να the negation is μη(ν), not δεν.
• Μη ξεχάσεις το κλειδί. -> Μην ξεχάσεις το κλειδί. — keep the final -ν before ξ (and before a vowel, κ, π, τ, ψ, γκ, μπ, ντ, τσ, τζ).
• Μην φύγεις τόσο νωρίς. -> Μη φύγεις τόσο νωρίς. — drop the -ν before φ; the rule cuts both ways.
• Θα ήθελα να είχα φύγει νωρίτερα. (as “I would have left earlier”) -> Θα είχα φύγει νωρίτερα. — the past potential is θα + pluperfect on its own, with no θα ήθελα in front.

Tips

• Read θα + imperfect as English “would”, not as a past tense. Θα ήθελα, θα μπορούσα, θα έλεγα are all about the present moment; only the pluperfect θα είχα φύγει looks back.
• In any transaction — ordering, asking for a form, booking a room — reach for θα ήθελα by reflex. The bare θέλω is not rude, but it is flat; with εσείς it can sound brusque.
• Test a μακάρι wish with one question: could it still happen? Yes → perfective subjunctive (μακάρι να βρέξει). No → imperfect (μακάρι να έβρεχε). Already too late → pluperfect (μακάρι να είχε βρέξει).
• Prefer μήπως over bare μη(ν) in fear clauses while it’s still new. Φοβάμαι μήπως πέσει can only mean “I’m afraid he may fall”, whereas a bare μη after a comma can be read for a moment as a prohibition.
• Remember the pair: μήπως … δεν for “afraid it won’t”, never μην δεν. One μη per clause.
• ας is the “let’s / let him” particle and pairs only with μην in the negative — ας μην το συζητήσουμε τώρα.
• The frozen να ήξερα!, μακάρι!, and ας ήταν! work as complete utterances on their own. Learn them as vocabulary; they buy you a natural-sounding reaction with no syntax to assemble.