Variable Properties vs Public Variables

[Rainbowinblack]

I've read many books teaching the basics of C#,
and all of them (+ couple of ppl who told me the same thing) say that using properties of local variables instead of making methods to change private variables or just making the a public variable...

They all said it was "better programming".

But i want to understand why...

lets say i've made the following class

namespace exampleNamespace
{
  class exampleClass
  {
     int firstVar;
     int secondVar;
  }
}

now, i want to let another class initiate and change the vars' values.

so what's the difference between this code

namespace exampleNamespace
{
  class exampleClass
  {
     public int firstVar;
     public int secondVar;
  }
}

and this code

namespace exampleNamespace
{
  class exampleClass
  {
     int firstVar;
     public int FirstVar
     {get (return firstVar)
       set (firstVar = Value)}

     int secondVar;
     public int SecondVar
     {get (return secondVar)
       set (secondVar = Value)}
  }
}

i know you can write only the get part - but it's just like making it readonly...

and i never really understood why you have to make the local variables private when you make methods to change them....
what's the point in that? :P

Roy