Harry Potter In Ancient Greek

[mahasacham]

I am trying to read "Harry Potter and the Philosophers Stone" in Ancient Greek and I came across a sentence that confused me. The Sentence is:

"Ἆρ´ οὐκ ἐφαντάσθην πάντα, ἔφη, ἐψευσμένος τι τῷ δοκοῦντι;"

I can guess at the meaning which I assume is "Don't all things seem fantastical, he said, to the one who assumes falsely".

The part I don't understand is the "ἐψευσμένος τι τῷ δοκοῦντι". I don't understand why "ἐψευσμένος" is a nominative participle. Does it go with the "ἔφη"? Just not sure why there is a nominative participle. Also what is the "τι" doing in the sentence?

Below is more of the paragraph to add context. Vernon Dursley (Dudley's father) thinks he is hallucinating when he sees a cat reading a map on the side of the road.

πρὸς δ´ ἁμαξιτὸν ὁδοιπορῶν, τὸ πρῶτον θαῦμα εἴδεν, αἴλουρον πινάκιόν τι γεωργραφικὸν ἀναγιγνώσκοντα. καὶ πρῶτον μὲν ἔλαθεν ἑαυτὸν τοιοῦτ´ ἰδών: ἔπειττα δὲ τὸν τράχηλον εἰς τοὐπίσω περιστρέψας, αὖθις προσέβλεψεν. αἴλουρον μὲν δὴ παρδαλωτὸν παρὰ τὴν ἁμαξιτόν ἑστηκότα, πίνακα δ´ οὐκ εἶδεν. καὶ πρὸς ἑαυτὸν ἐννοῶν Ἆρ´ οὐκ ἐφαντάσθην πάντα, ἔφη, ἐψευσμένος τι τῷ δοκοῦντι;

[jeidsath]

The English being translated is not going to help us out much, unfortunately: "What could he have been thinking of? It must have been a trick of the light."

"Ἆρ´ οὐκ ἐφαντάσθην πάντα, ἔφη, ἐψευσμένος τι τῷ δοκοῦντι;"
"Did I not imagine it all, he said, being deceived by one part in regards to the thing seen?"

Ie., did he see the αἴλουρος but imagine the πινάκιον γεωργραφικόν? Though I'm uncertain about τῷ δοκοῦντι as "in regards to the thing seen."

[mwh]

somewhat fooled by what (merely) seemed (to be the case). τω δοκουντι as distinct from τω οντι, what actually was. Seeming vs. being, as often in Plato and subsequent philosophers, δοκεῖν/εἶναι, schein/sein.

There was a previous thread on the Greek translation, which is very accomplished. Plato and Lucian are evidently the main stylistic models.

[mahasacham]

Excellent mwh!! I thought that the τι was adverbial but the distinction between δοκεῖν/εἶναι is very insightful. This distinction is gonna go a long way in my understanding of these authors. I am quite familiar with "τῷ ὀντι" being used to mean reality or what actually is.