Mental Model · Benjamin Graham
Margin of Safety
Personal recommendation by Marshall Delpé. Not made by Marshalldelpe.com.
Margin of Safety
Mental Model · Benjamin Graham·

Leave room for being wrong, because you will be, eventually.
What it does: Builds a buffer between what you expect and what you can survive. Engineers design a bridge rated for 30,000 lb when they expect 10,000 lb trucks; Benjamin Graham applied the same idea to investing — only buy when the price sits well below a conservative estimate of value.
Who it's for: Investors, planners and anyone whose decisions depend on forecasts that might be wrong — which is every forecast.
Why I use it: I assume I will be wrong some of the time and plan so that being wrong does not ruin me. That means an emergency fund, low debt, buying assets at sensible prices and never betting everything on one outcome. In healthcare we build redundancy into every critical system for the same reason. Survival comes first, because you cannot compound if you are knocked out of the game.
Tradeoffs: Too much margin means sitting on cash, passing on good opportunities and growing more slowly. Estimating "true value" is itself uncertain, so the margin is only as good as the analysis behind it.
Alternatives: The Intelligent Investor by Benjamin Graham (chapter 20 is the source), Margin of Safety by Seth Klarman, Nassim Taleb's Antifragile on building systems that benefit from shocks.
This is a personal recommendation, not a paid promotion.
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The 48 Laws of Power
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Read it so you can spot the person at work who already did.
What it does: Robert Greene distils 3,000 years of history — Machiavelli, Sun Tzu, Bismarck, Louis XIV, con artists and courtesans — into 48 laws describing how power is gained, held and lost. Each law comes with historical stories of people who followed it and people who broke it, plus the reversal: when the law doesn't apply.
Who it's for: Anyone who works with people — in a hospital, a company, a negotiation or an investment deal — and wants to understand the unspoken dynamics at play. Especially useful if you've ever been blindsided by office politics or someone else's agenda.
Why I use it: I read it as a field guide to human behaviour rather than a playbook. It helps me recognise manipulation when I see it, protect my reputation, and stay calm instead of reacting. Laws like "Never outshine the master", "Guard your reputation with your life" and "Say less than necessary" have saved me from mistakes at work. It pairs well with Munger's psychology of human misjudgment, which you'll find in Poor Charlie's Almanack.
Tradeoffs: Some of the laws are ruthless, and following them literally can cost you trust and relationships. It's long and repetitive in places, and it's best read defensively — to understand power — not as permission to be cold or deceptive. The stories are selective history, not rigorous research.
Alternatives: The Laws of Human Nature and Mastery by Robert Greene, How to Win Friends and Influence People by Dale Carnegie (the warmer approach), Influence by Robert Cialdini (the research-backed version).
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The Art of War
Book · Sun Tzu·

Ancient battle advice that works surprisingly well on salary negotiations.
What it does: An ancient Chinese treatise on military strategy, traditionally credited to the general Sun Tzu, written around the 5th century BC. In 13 short chapters it covers planning, positioning, deception, intelligence and when to fight — and when not to. Its core idea: the best victory is the one won without fighting.
Who it's for: Anyone dealing with competition or conflict — in business, negotiation, investing, sports or office politics — who wants timeless principles about preparation, patience and knowing the terrain.
Why I use it: It is short enough to reread every year, and every reread lands differently. "Know the enemy and know yourself" maps directly onto investing and staying within your circle of competence, and the emphasis on avoiding unnecessary battles is a reminder that the strongest position is often the one where you never have to fight. It pairs naturally with The 48 Laws of Power.
Tradeoffs: The aphorisms are compressed and sometimes cryptic, so translation quality matters a lot. It is easy to over-apply military metaphors to everyday life, and the original is about war, not business — the connections take reflection to make.
Alternatives: The 48 Laws of Power and The 33 Strategies of War by Robert Greene, The Book of Five Rings by Miyamoto Musashi, and On War by Carl von Clausewitz.
As an Amazon Associate I earn from qualifying purchases, at no extra cost to you. I only recommend what I actually use.