I agree Page that we often dismiss the power of words.  And of course I love the reference to teachers in your passage.  :)  A big part of this discussion has to be the idea that something small can have a big impact as in your text, a rudder, a bit, a few words.  More importantly, we often give more weight to the negative than the positive, as in this quote:  "Tell a girl she’s beautiful and she’ll believe it for a moment. Tell a girl she’s worthless, and she’ll believe it for the rest of her life." ~unknown

In the end you are so right.  We can use our words to tear down or to build up.  It is our choice.