As a personal low nothing probably ranks as far down the scale for Alastair Campbell as the nervous breakdown he suffered in 1986.
Marathon man: But it was his professional life normally in the spotlight
By his own admission it was fuelled by a combination of alcohol and, at the age of 29, taking on a job - news editor at the now defunct Sunday Today newspaper - he was not equipped to perform.
From his point of view the professional highs since then have surely been many - from rising to political editor on the Daily Mirror, to the way he steered Tony Blair through the tricky
days of Diana, Princess of Wales', death.
But for his many critics the lows have been as significant, from the poor PR that resulted from Cherie Blair's financial involvement with a convicted Australian conman to his alleged description of Chancellor Gordon Brown as "psychologically flawed".
On the positive side of Mr Campbell's balance sheet there lies the crucial role he played in transforming Labour's election fortunes.
From his vantage point on the Labour-supporting Mirror, the party's 1992 defeat under Neil Kinnock was a defining moment, one he was determined to help reverse.
After joining Mr Blair's staff in 1994, he quickly rose to the head of the media operation to play a pivotal role in the 1997 landslide.
Neil Kinnock is still among Mr Campbell's friends
He is widely credited with the new prime minister's famous election morning arrival in Downing Street through a sea of waving Union Jacks, as he is with the "People's Princess" statement delivered a few months later on Princess Diana's death.
The Kosovo campaign - and subsequently the war in Iraq - showed a media communicator at his peak, working under intense pressure and transforming Nato's public relations machine almost overnight.
After the second election victory - an historic one for Labour - the ever-present accusations of spin quickly reached a fresh crescendo, but Mr Campbell again demonstrated his good judgement by announcing he was stepping down from day-to-day media briefings.
There are likely to have been many occasions when Mr Campbell prevented damaging publicity - or worse - for the government that will only emerge on publication of his diaries.
But overall it is probably the accusation of spin that has been Mr Campbell's single biggest professional low.
It has dogged him throughout his entire career with New Labour.
Among the moments that stand out are his role in Peter Mandelson's second resignation, when the press chief sealed his ruthless reputation by reportedly hurrying the beleagured cabinet minister to stand down and all but publicly claiming he had been misled by him.
In the wake of the Queen Mother's funeral in 2002, a furious row broke out over reports of an Alastair Campbell-orchestrated attempt to engineer a more prominent role in the proceedings for Tony Blair. Mr Campbell, and the prime minister, denied everything.
Then there were the leaked e-mails from a Department of Transport special advisor seeking to discover the political affiliations of a Paddington rail crash survivor who had criticised the government.
Mr Campbell insisted there was no evidence to link the e-mails to Downing Street, but he joined the chorus of ministers who apologised for it.
Latterly, his admission of "regret" for mistakes in the so-called "dodgy dossier" on Iraq's weapons of mass destruction was a dismal professional low point.
And many commentators saw his angry appearance on Channel 4 News at the height of the recent dossier row with the BBC as an uncharacteristic lapse of judgement.
Although the headlines are bound to link the Hutton inquiry with his resignation announcement, it is not yet clear whether the events surrounding it will forever tarnish Mr Campbell's reputation, or whether the balance of highs and lows across his whole career is in the red or black.
Perhaps the best judge will be the one his employer, Tony Blair, favours: history itself.