Optical Illusion

"Hi Danny! 
      Here's another picture postcard of Gibraltar Dam.  See that little van in the background?  If you hold your thumb over it and look at the picture, the flood gates look small.  If you take your thumb off the van, the flood gates look humongous.  Try it....see what I mean?  That's what's called an optical illusion.  It's kinda like how Cukie (my bird) used to fluff up his feathers to look really big, but when he was hopping around on the ground he looked really small.  Or how it looks like your dad has lots of hair, but really, it's a wig.  ha ha. kidding.
      'wish you were here!'
              Love,
                   Auntie"