Imagine the above picture, with me standing in-between. Both dogs have leather leashes attached to harnesses. Calvin (in the background) is pulling hard, trying to get ahead. Hobbes (foreground) is lagging behind, enjoying every scent and leaf he comes across. That's how I give our dogs walks every day, with my arms and hands pulled in two different directions. No matter what, I have to cater to one or the other, until they walk together.
They remind me of readers (below). Calvin (on the left) is interested in the next page, not willing to take his time to savor the words or even read them all. Hobbes (on the right) not only wants to know what's on the page, but under it, around it, and probably through it, knowing him.