Historian Edmund Gibbon's view that 'the decline of the Roman Empire began with the end of the era of the Five Good Emperors' remains unchanged to this day.
Why did empires fall into decline during the era of the great iron emperors?
From the last emperor of the 'Era of the Five Good Emperors', Marcus Aurelius, to the soldier emperor Septimius Severus, the 'History of the Decline and Fall of the Roman Empire', written by Nanami Shiono, begins, slowly decaying from the 'head' onwards.

Marcus Aurelius left behind a book that posterity called the
Thanks to this, he came to be called the 'Iron Emperor', but as the title suggests, it is not a book that discusses philosophy from an academic perspective.
For him, as the Roman Emperor, defeating the barbarians was his public duty, and the book was merely a small book in which he recorded his thoughts in his spare time on the battlefield while carrying out his official duties.
However, as expected from someone who enjoyed philosophy since childhood, the book is known to be full of reflection and contemplation.
The praise paid to the book by modern Western intellectuals was that it was 'the best expression of the ethics of the ancients' and 'the sincere cry of a noble soul.'
Plato also said that it is ideal for a country to have philosophers in charge of politics.
Leaving aside the debate about the validity of this statement, modern intellectuals who experienced the Enlightenment would consider Marcus Aurelius to be the only case in history where Plato's ideal was realized.


- It is unacceptable to endlessly repeat the debate about whether humans can be fair and good.
A time is coming when only fair and good behavior is required.

This was the 'voice' that came from the mouth of the supreme authority that ruled the great Roman Empire.

--- pp. 17-18