These are two identical, straight lines. Kind of boring, right? But what happens when you change what’s going on around them? All of a sudden, the lines look like they’ve changed size in relation to each other; they could shrink and grow; they might change to different shades; they may stretch and compress; and they could bend, buckle, or even change directions. But even though it would seem like the lines themselves are changing, the only thing that’s actually bending or buckling.