what makes early English literature so difficult to read? I

Discussion Topic (1 paragraph, not more)
Early English literature was written in Old English, which is vastly different from Modern English. Often, these texts are translated into more accessible language for modern readers. When reading these older forms of English, it can be difficult to understand the meaning, even if the language has been modified.
1. In your opinion, what makes this literature so difficult to read? Is it the vocabulary, the characters, the type of storytelling, the density of the language, or something else?
2. As you progressed through Old English texts to Middle English to Modern English, how did your understanding of the literature change?
3. Can you explain what caused the change?