Never invest in any idea you can’t illustrate with a crayon.

Attributed to famed Fidelity Magellan fund manager Peter Lynch, this line encapsulates his preference for plain, comprehensible businesses over opaque stories and fashionable complexity. The “crayon” test implies that if an investment thesis can’t be explained simply—so simply it could be sketched for a child—then the investor likely doesn’t understand the drivers of earnings, risks, and valuation well enough to commit capital. It also cautions against being seduced by jargon, elaborate models, or speculative narratives that substitute for clear economics. In Lynch’s broader investing philosophy, simplicity is not anti-intellectual; it is a discipline that forces clarity about what truly makes a company succeed.