The Mensarius Oath: When Ancient Banking Meets Modern Ethics

I stumbled across something called “The Mensarius Oath” recently and pulled the string that led from ancient Roman banking to modern venture capital ethics. It’s a story about how we keep trying to solve the same fundamental problem: how do you make finance serve society instead of the other way around?

The Original Mensarii

Our story starts in ancient Rome, 352 BCE. The Republic is facing a debt crisis. Citizens are drowning in obligations they can’t meet, social unrest is brewing, and the normal mechanisms of private banking aren’t cutting it. So the state does something interesting: they create the quinqueviri mensarii: a five-person commission of public bankers tasked with solving the crisis.

The mensarii (from mensa, meaning “bank” or “table” where business was conducted) weren’t your typical Roman financiers. While the argentarii operated as private bankers focused on profit, the mensarii were public officials with a different mandate: use state resources to help citizens escape crushing debt and prevent social collapse.

Here’s what made them different:

• They were appointed during emergencies, not operating as permanent institutions
• Their goal was social stability, not profit maximization
• They provided relief to citizens who could offer security, using public funds
• For those who couldn’t provide security, they managed fair asset transfers to creditors

Think of them as ancient Rome’s version of a financial crisis response team, but with actual teeth and public accountability.

The Modern Revival

Fast forward to 2020. A group of venture capitalists, led by VC Lab, decided the finance industry needed its own version of the Hippocratic Oath. They borrowed the term “mensarius” - banker in Latin - and created what they call the Mensarius Oath.

Here’s the actual oath text from VC Lab:

The Mensarius Oath v2

As a financial professional investing with personal or investor capital, I pledge to uphold these values. If determined by myself or a panel of my peers that I have violated these values without reconciliation agreed between all involved parties, then I will voluntarily leave the industry.

Integrity: I vow to invest with integrity, ensuring my actions benefit humanity and consciously avoid harm to any parties.

Excellence: I commit to maintaining the highest professional standards, setting an exemplary ethical benchmark in finance.

Fairness: I endeavor to be fair in my dealings, standing against abuse of power, unfair advantage, seduction, corruption, or mistreatment.

Equality: I pledge to promote inclusivity and equitable treatment in all financial endeavors, consciously working to reduce inequality.

Respect: I promise to treat individuals and opportunities with the respect and the attention deserved in business interactions.

Transparency: I affirm to be transparent and honest in dealings with investors, founders, and colleagues.

Confidentiality: I swear to safeguard private, confidential, or personal information, keeping it safe from public or other unwanted disclosure.

Growth: I am resolved to embrace feedback from clients and peers, committing to ongoing personal and professional growth.

It’s explicitly modeled after medical ethics, asking finance professionals to swear they’ll use their power responsibly. The idea is to transform venture capital “into a force for good.”

Why This Matters

This matters for obvious reasons: what we, as a society, do with our money is important. When the capital being invested is often from things like pensions and endowments it’s closer to home than many realize. I’ve also raised VC for startups myself and I can tell you: the investment matters. Companies live or die based on ability to raise, so when the financing happens for less than ideal reasons, that’s bad for the industry and economy as a whole.

The Roman mensarii understood that during crises, normal banking relationships break down. When citizens can’t pay debts, private lenders don’t just shrug and walk away, they seize assets, which can destabilize entire communities. Someone needs to step in with a broader perspective.

The modern Mensarius Oath recognizes something similar about venture capital. When you’re deploying billions of dollars into early-stage companies, you’re not just making investment decisions, you’re shaping what technologies get built, what problems get solved, and ultimately, what kind of future we create.

That degree of influence and power matters societally.

The Vibe Check

Do I think the Mensarius Oath will transform venture capital? Probably not on its own. Voluntary ethical commitments are only as strong as the systems and peer pressure that enforce them.

But do I think it’s pointing toward something important? Absolutely. Whether it’s ancient Roman debt crises or modern tech bubbles, we keep learning the same lesson: finance shapes society, so society needs ways to shape finance back.

The mensarii understood this 2,400 years ago. Maybe it’s time we took their example more seriously.

The modern Mensarius Oath is promoted by VC Lab, a venture capital accelerator based in Palo Alto.