"Dear Monica," he wrote, congratulating Ms Lewinsky on her public silence so far, "if you go public ... those who have a personal stake in Bill Clinton's presidency ... will come roaring to his defence ... You've seen the way Mr Clinton's defenders have dealt with accusations, whether founded or not, by Gennifer Flowers, Paula Jones and Kathleen Willey."
It was a timely warning. Ms Lewinsky had barely completed her testimony at the Washington Court House last week than her detractors were tuning up.
Most blatant is a series of articles in this week's National Enquirer, a gossipy tabloid which gives the lowdown on the stars and the soap operas.
Ms Lewinsky's face stares out from the cover, with the headline: "Monica's Story - 'I Just Wanted Bill To Love Me'. Inside her bizarre world." Underneath, a boxed headline read: "The Abortion Shocker".
Inside a double page is headed in red: "Strange, sick world of Monica Lewinsky". There is a reference to an abortion she supposedly sought after coming to Washington in 1995, and a note attributed to a psychiatrist, Dr Anthony Pietropinto, who says: "Call it a sick fantasy if you will, but she believes she meant something to this president."
There are also quotations, attributed to President Clinton - via unidentified "friends" - saying: "The woman is dangerous. She hallucinates. She fantasises. I don't know if she even knows what the truth really is any more."
In the mainstream media, the National Enquirer is not taken seriously. The so-called "supermarket tabloids", however, have covered aspects of the President's love life that the mainstream has shunned.
More oblique, but also damaging to Ms Lewinsky, was an interview on the CNN show Larry King Live with a woman called Julie Steele.
Ms Steele has alleged for the best part of a year that she lied to a Newsweek reporter to help her then friend, Kathleen Willey.
Ms Willey had told the same reporter of an incident when, she alleged, President Clinton had groped her when she had gone to him to ask for a job. Ms Steele was to tell the reporter that Ms Willey had told her of the incident just after it had happened.
Ms Steele now wanted to tell the world once again that she had lied to help her friend. If Ms Willey had invented the incident, then the viewers, with Ms Lewinsky fresh in their minds, should conclude the likelihood was that Ms Lewinsky was also the victim of a vivid imagination.
Throughout the Lewinsky saga, the White House had been careful not to be seen to discredit her, but several of the women associated with Mr Clinton's past have complained of attempts to destroy them.
John Dean alluded to them in his warning. He also warned of the length of political memories in Washington. "Unbelievably nasty and false efforts to discredit me", he said, went on for 25 years.
To minimise the damage, he advised, Ms Lewinsky should defend her reputation as strenuously as possible.
"The only way to stop them is to go after them. Otherwise they will try to devour you. I know."Reuse content