Back in the mid-1700s, Samuel Johnson observed that there were two kinds of knowledge: that which you know, and that which you know where to get. It was a moment when cheap and abundant print coupled with reliable postal networks triggered an information explosion that dramatically changed the way people thought. [...] Now the Internet is changing how we think again. Just as print took over the once-human task of knowing, cyberspace is assuming the task of knowing where to get what we seek. [...] Now we revel in search, but most of what we search for isn't worth seeking, as the top search lists on Google, Yahoo and Bing make clear. [...] The Internet has changed our thinking, but if it is to be a change for the better, we must add a third kind of knowledge to Johnson's list — the knowledge of what matters.