I read part of Genji Monogatari during my Japanese studies as an undergrad. It's nearly 1,000 years old and it's absolutely not the same language that's spoken

I read part of Genji Monogatari during my Japanese studies as an undergrad. It's nearly 1,000 years old and it's absolutely not the same language that's spoken in modern Japan. How much of anything written that long ago could a normal native English speaker understand? It's just not a reasonable thing to expect from the general populace.