Exodus Chapter 17 is very quick and easy. Basically, the Israelites are still in the desert and they're pissed that there's no water. In fear of them, Moses asks God what's going on with the water supply and God tells Mo to tap a rock. Moses does so, and behold, water comes out of it!
The authors of the Bible don't really care about transitional material. After the watering episode, the Amelekites attack the Israelites. In the battle, as long as Moses holds both of his hands up into the air, the Israelites are winning; but if he lowers his hands, the Amelekites are winning. The battle goes on for so long that Moses is propped against a rock and his two homeboys held the hands up for him.
Chapter 17 lays out the case about how superstitious people were back then, and by extension how superstitious people are today. Superstition means a belief that isn't based on reason. If Moses actions were repeated today (lifting your hands affects the outcome of the battle), the general doing so would be thought of as eccentric at best. If Generals Patton or Petraeus held their hands up during a heated battle, most folks today would think they were crazy. In fact, they'd probably get fired.
But still, there are people today who let stories like this slide, believing that these events happened back then but can not be replicated today. That's an irrational belief itself, and I'd venture to say that it is superstitious as well.
Next time, the 10 Commandments. Are the ones we are familiar with the 'correct' ones, or are they even moral?