Legendary fund manager Peter Lynch said that you shouldn't invest in any idea you couldn't illustrate with a crayon.

I'm not much for crayons, but I do love the pithiness of that line. It's something we regularly preach at the Fool: Don't buy what you don't understand. And if you can't simply sketch out a company's business model -- how it, you know, actually makes money -- then maybe you shouldn't be investing in it.

Today I'd like to share a very simple visual of one of my own portfolio holdings, the surgical robot pioneer Intuitive Surgical (Nasdaq: ISRG). Here's my attempt to encapsulate the company's business model:

Disagree with me? Think I missed something? General thoughts on this exercise? I'll be reading the comments below, so please share. And if you haven't already, be sure to follow Intuitive Surgical using the Fool's free new My Watchlist tool.

The da Vinci patient cart image is (c)2006 Intuitive Surgical Inc. 

Fool.com executive editor Brian Richards owns shares of Intuitive Surgical. Intuitive Surgical is a Motley Fool Rule Breakers pick. True to its name, The Motley Fool is made up of a motley assortment of writers and analysts, each with a unique perspective; sometimes we agree, sometimes we disagree, but we all believe in the power of learning from each other through our Foolish community. The Motley Fool has a disclosure policy.