Last shot from the book. I'm convinced that you simply can't judge (from these pix) how enormous Half Dome really is. Since we learned that we get our depth cues from size, I think they're an optical illusion  - HalfDome is so enormous that it simply appears *closer*, when in reality, it's much further .. and much bigger, than it appears. To the trail! 

Next -> On the trail at Vernal Falls