How different are the ancient and modern Greek languages?

[Hampie]

I were to learn ancient Greek, to what extent would I be able to understand modern Greek? do you know about it?

I know neither, but, I know the difference in time. If you consider German, English, Swedish and Netherlands/Dutch they were all the same language long after Attic was spoken in Greece. Latin has since roughly that time evolved into Spannish, Italian, Brazilian, Romanian and Retromanish. Though some words might be very similiar and some things exactly the same – other has changed a lot. All languages that evolved out of Latin (except for Romanian) has lost allmost all noun inflections.

However, the educated in Greece did try to keep the written language close to koinè for very long, and it was, I think, first in the 70’is they abolished polytonic spelling – something that had not been pronounced for about 1000 years I think. However, you will probably find vocabulary easier to learn and by knowing the alphabet and being able to read it, it will help to gian reading ability faster.

[Adelheid]

I'm learning modern Greek right now and although it helps that I already knew ancient Greek, the languages were different enough for me to be totally not able to make sense of modern Greek.

Knowing the alphabet helps, being accustomed to declinations and conjugations helps, some words have retained the original meaning, but you are basically learning a new language.

A good book suggested on this forum earlier, about the development of Greek through time, is Geoffrey Horrock's 'Greek: A History of the Language and its Speakers'.