The Greek (ancient) is more difficult than the modern, and the Ancient Greeks were cleverer than the modern because of the difficult language.
For a Chinese is easy to learn Russian because it has a difficult first language.
For a Greek philologist who speaks Latins and Ancient Greeks is easy to learn Modern Russia.
For me, a person with a BSc from An American College (CIS) and an MSc from British University (Computers) is difficult (was) to learn Modern Russian, and only Christ and His mother had helped me.
According to Rocket languages, we need 600 hrs for a Latin Origin and for others like Russian 1200 hrs. I think level B1.
The language train the brain and create a way of thinking
Ancient Greek Philosophy is a child of the language, even today people who know to read and write Ancient Greek are better at thinking.