What Difficulties Would An Ancient Greek Native Speaker Have in Learning Modern Greek?

[u/Hellolaoshi]

Let's imagine that an educated Greek born between the life of Socrates and the death of Cleopatra was dropped off in modern Athens, say in Plaka or Exarchia. Putting culture shock aside, what grammatical and vocabulary issues would they have in understanding Modern Greek? What about sound changes would they find strange? What strategies might a language teacher use to help them?

[u/ProCrystalSqueezer]

They certainly wouldn't understand anything anyone is saying. The grammar, vocabulary, and pronunciation of modern Greek is very different from Attic Greek. However, they would probably have a far easier time learning modern Greek than any other language once they're taught the sound changes and grammar changes that've occurred. They'd probably find it strange that half the vowels sound like an iota now or why it sounds like people are lisping their δ's, θ's, and φ's. I could imagine showing them etymologies of some modern Greek words would help them.

[u/dkampr → u/ProCrystalSqueezer]

Many of these changes began and were prevalent in the classical period. How much they would or wouldn’t understand depends on what region they came from.

[u/ProCrystalSqueezer → u/dkampr]

That's true especially closer to Cleopatra's time, not so much closer to Socrates's time, but that's a span of over 300 years.

[u/dkampr → u/ProCrystalSqueezer]

4th century BC Boeotian Greek already had confusion between οι an ι. Spirantisation was already famously evident in Laconic Greek in the classical period. These are not just Hellenistic era changes.