Somebody explain this cat behavior (as if cat behavior can be explained).

[Ocelot II]

I have two big gray brothers, Chet and Dave. Chet is easy-going and doesn't fret much about what goes on outside. Dave, on the other hand, is very watchful and runs from window to window to see what's going on out there - maybe another cat, or squirrels, or rabbits, or figments of his imagination. What I don't get is that when Dave runs from one window to another, instead of taking the shortest route straight across the floor, he jumps from a table to a desk to a bookshelf to another small table to a windowsill. He traverses the circumference of the room on surfaces, ignoring a basic geometric principle, C=2πr, when if he'd just run across the floor on the diameter he'd get to the other window faster (the room isn't circular but the furniture layout creates a rough circle). Is it that cats don't understand geometry, or that he wants to stay up higher so he can see the window at all times? Is this a normal cat thing?