There are laws of nature--like gravity, thermodynamics, and Newtonian principles--that help explain our reality. And then there are rules of thumb, many of which cannot be scientifically proven and yet are clearly true. Pocket-sized, practical, and studded with whimsical illustrations, this small but mighty book offers us forty-four of the best unwritten laws and mental models for posterity.

These include:

• Parkinson's law, which says that any meeting, project, or task will take at least as much time as you've allotted for it.
• The Pareto Principle, which explains how 80% of your results come from 20% of your efforts.
• And Murphy's Law, which dictates that if something can go wrong, it will .?.?.

Some of these truisms are world-famous; some well-kept secrets. Some are tongue-in-cheek; others imbue wisdom. But they all have one thing in common: They illuminate working life better than any MBA. From KISS (Keep It Simple, Stupid) to the IKEA Effect (we're partial toward things we've had a hand in making), these models will help you manage your time, make smarter decisions, and survive anything the world throws at you.