THE American comedian Oscar Levant once quipped, "I knew Doris Day before she was a virgin". By the same token, some of us knew Martin McGuinness before he was a statesman.
That's why choosing him as their presidential candidate is such a massive risk for Sinn Fein to take -- and one that could well blow up in their faces between now and October 27.
There is a 20-second clip on YouTube that anybody thinking of voting for McGuinness should watch. It shows the Art Garfunkel-lookalike standing in front of a wall covered in graffiti, warning that any of his comrades who help the other side know exactly what the punishment will be.
"Death?" asks the interviewer. "Death, certainly," is the calm reply.
For obvious reasons, McGuinness will try to present a very different image in the weeks ahead. He will campaign as a teetotal family man who enjoys fly-fishing, writing poetry and watching Manchester United. He will boast about his role in the Northern peace process, ignoring the fact that he was one of the terrorists who made it necessary in the first place.
Nobody should be fooled. McGuinness's friendship with Ian Paisley may have caused them to be dubbed the Chuckle Brothers, but in fact one of his main characteristics is a total lack of humour. In reality, he is a cold-eyed, stone-hearted fanatic -- and, barring a personality transplant, a completely unsuitable candidate to be the next President of Ireland.
McGuinness likes to pretend that his Provo past is all a matter of record. It is quite true that, unlike Gerry Adams, he has at least admitted to being a member of the IRA. What exactly he did for them, however, is still extremely murky -- and whether or not he ever murdered anyone himself, there is absolutely no denying that his hands are drenched in blood.
McGuinness has also put forward the fiction that he left the IRA in the early 1970s, shortly after being imprisoned in the Republic for the possession of explosives. All serious historians of the Troubles agree that this is a total lie. As recently as 2005, justice minister Michael McDowell claimed that both Adams and McGuinness were on the IRA's army council -- suggesting that they were the military masterminds behind a campaign that eventually claimed over 1,800 lives.
One of those murders, in particular, has been closely linked with the man who would be president. Frank Hegarty was a British agent in the IRA, shot in the head and dumped on a roadside with his eyes taped up in 1986. According to his mother, he only returned to his native Derry because McGuinness assured him he would be safe -- and on the anniversary of his death, she placed a newspaper advert condemning the 'Judas' who had betrayed her son.
The McGuinness for President campaign is based on the notion that Irish people have very short memories. Maybe, but they are surely not that short. If his sinister past is dragged out into the light where it belongs, then the Shinners may start wishing they had run a fresher face such as Mary Lou McDonald instead.
This contest will also represent a big challenge for media interviewers, particularly the RTE and TV3 presenters who will host the televised debates. Will Pat Kenny, Miriam O'Callaghan or Vincent Browne have the guts to pursue McGuinness on these issues and refuse to be fobbed off by bland denials? If not, will other candidates take him on or are they too afraid of looking negative?
McGuinness's candidacy has also put the David Norris affair into some sort of perspective. If the Senator is to be ruled out as a potential president for writing a letter, then how can the Butcher of the Bogside be given a free pass?
Martin McGuinness has got away with an awful lot in his life. Let's not allow him to get away with fooling the people of Ireland as well.