>>>I was wondering if anyone on here knows how substantially different modern Greek is from ancient Greek (i.e. the Greek of Aristotle)?<<<
I am told that there are some isolated pocket Greek communities who still speak at least a version of the Attic dialect [Plato and Aristotle], and that it is called, if I recall, Kathervouska Greek - That language was tonal, as the modern Greek is not, and the modern is not well comprehensive of the ancient at all. We had tow guys from Athens in my Greek 101 class, and they were stars for the first two weeks, as we struggled to just get the alphabet, but then, when vocabulary and sentence construction proceeded, they were just as much awash in study as were the rest of us mon Greeks.
Much the same is true for the Greek Bible, which is not at all well understood by modern Athenians who hear it read in services. The old women in the Churches practically have it memorized from their lifelong attendance at services in which it is read, and they pronounce according to modern Greek standards. In 2000 years, the language has evolved, but much less that English in, say, 500 years... And the language of Atistotle was the 'high' Greek of 500 years before Christ, when Greek was aflowering its radiance that the west did not receive until many centuries later with their 'discovery' of the Attic texts and culture in the middle ages, and the ensuing effort to accomodate them into their religion. [faith vs reason, and all that...] The East had dealt with those matters long before, and had done so in Greek, and had laid the philosophers pretty much to rest. The west took them and created the enlightenment and the industrial revolution... [Not to mention Protestantism...]