A.G. Lafley, Procter & Gamble's CEO (and now Chairman), penned an HBR article in May that I think best summarizes the job of the CEO. Get your assistant to buy it -- and you should read it -- very good stuff.
To give a taste, here's my summary, plus a few of my favorite quotes.
Lafley argues that because the CEO doesn't report to anyone within the enterprise, only he can truly advocate for customers and shareholders. As Peter Drucker, Lafley's guru, stated: "The CEO is the link between the Inside that is 'the organization' and the Outside of society, economy, technology, markets, and customers. Inside there are only costs. Results are only on the outside."