What is the reason for the arrangement of the parts of the Qur'an in the form found in the Book of Allah?

The Companions arranged the Qur’an in a divinely ordained order at the command of the Prophet, may Allah bless him and grant him peace. As for the division of the Qur’an into ajza’ (parts), ahzab (sections), and arb’a (quarters), this was not divinely ordained but rather an interpretive effort by the scholars. This division was formalized during the era of the Tabi'in (successors of the Companions) by a committee formed by Al-Hajjaj ibn Yusuf Al-Thaqafi, by order of Abd al-Malik ibn Marwan, to facilitate memorization and recitation. It is worth noting that the designation of the beginnings of the ajza’ and ahzab is a scholarly interpretation and varies among different copies of the Qur’an.