What is the purpose of the anecdote with which david foster wallace opens the speech? what is the effect of his returning to the line "this is water" again near the end of the speech and repeating it there?

i would like to compare these two interpretations of the crucible : 1) eric christ's interretation and wade bradford's interpretation. the main differences between there interretaions is that in the first one you can notice direct link to joseph mccarthy whereas the second one represents how the town is filled with hysteria.the second interpretation shows that author believes that the story   about puritan town in salem is based on actual events while the first example shows the sencible reference to sort of bias.

explanation

old disney was more kid oriented as appose to new disney it's more teen oriented.i guess what i'm trying to say is new disney is way more mature and out there then old disney. for instance all you see in new disney is bf/gf drama and old disney it was nothing like that. kids are growing up and as coorpations like disney, nickolden etc they tend to follow what kids follow so they can have more views . therefore   they have inferred   that now days kids want to have relationships and stuff so that's what disney gives them.