Arcanum imperii

The Rules Lawyer
3 min readApr 13, 2021


Relief from Trajan’s Column, showing legionaries traversing a pontoon bridge. Photo by Conrad Cichorius (1896), in public domain. Retrieved from Wikimedia Commons.

“Although Nero’s death had at first been welcomed with outbursts of joy, it roused varying emotions, not only in the city among the senators and people and the city soldiery, but also among all the legions and generals; for the secret of empire was now revealed, that an emperor could be made elsewhere than at Rome.”

This celebrated passage of P. Cornelius Tacitus’s Histories (I, 4) refers to A. Vitellius’s accession, in 68 AD. It was the first time that the legions had proclaimed a new emperor. It would not be the last time.

Tacitus’s arcanum imperii, “secret of empire”, was much later summarized in a more general sense by general Douglas MacArthur: “rules are mostly made to be broken”.

The “rule” according to which emperors would only be made emperors in Rome worked as a rule only while people consented to it. When Vitellius and his legions refused to be bound by this rule, it had no intrinsic power to enforce itself.

No rule has this power. All rules must be implemented and enforced by people. Every rule is created by humans… and can be changed, amended, ignored, broken, rescinded, destroyed by humans.

All through recorded history, the same secret has been revealed again and again. We often take comfort in rules; but, as attested by William A. Ganoe, what MacArthur said in full was “rules are mostly made to be broken and are too often for the lazy to hide behind.”

In the past couple of centuries, our culture has taken comfort in what we call the Rule of Law. According to this principle, all members of a society — including those in government — are considered equally subject to the law.

But what happens when those in government — in power — decide to willfully break the law, even flaunting this and reveling in it? The law may not oppose them by itself. The rules are not self-enforceable.

The problem is not new. We go back to the time of Tacitus, but now to remember the Satires of D. Iunius Iuvenalis (Satire VI, lines 347–348). Quis custodiet ipsos custodes? Who watches the watchmen?

Not only the problem is not new, it was already old in the time of Tacitus and Iuvenalis. We have no definite answers to it, if indeed such answers are even possible.

Are game rules different in this regard? Usually, no. If a group of players decides to play Rummy with no wild cards, no game police will show up at their door and force them to use wild cards. There are many role-playing games which state quite clearly that their rules can and should be changed. From this freedom come house rules, variants, and ultimately many new games.

However, digital games present an interesting twist here. Although the rules in such games are likewise created by humans, they are enforced by digital devices, which also have full control over the game environment — the magic circle in which the game unfolds.

It remains to be seen whether this presents new questions, or just new perspectives on very old questions.



The Rules Lawyer

I’m Luiz Cláudio Silveira Duarte, polymath and philomath, researching games, players and rules. My personal page (in Portuguese) is