Clinton, the meaning of "is"

Years from now, when we look back on Bill Clinton's presidency, its defining moment may well be Clinton's rationalization to the grand jury about why he wasn't lying when he said to his top aides that with respect to Monica Lewinsky, "there's nothing going on between us." How can this be? Here's what Clinton told the grand jury (according to footnote 1,128 in Starr's report):


"It depends on what the meaning of the word 'is' is. If the--if he--if 'is' means is and never has been, that is not--that is one thing. If it means there is none, that was a completely true statement....Now, if someone had asked me on that day, are you having any kind of sexual relations with Ms. Lewinsky, that is, asked me a question in the present tense, I would have said no. And it would have been completely true."