Van Persie signing is a landmark moment for Man Utd
Sir Alex Ferguson has made an exception to his rule for an exceptional talent. Manchester United's manager has moved away from his zealous investment in the younger market to sign Robin van Persie.
Ferguson's transfer mantra in recent seasons has been "value" - so it is a measure of the size of the statement he and United want to make that he is prepared to pay £24m plus a lavish salary for Arsenal's 29-year-old double footballer of the year.
For Arsenal, there will be injury at seeing their leader and main attacking threat leave. There is the added insult that after questioning their direction and ambition he has chosen to be the first player to switch from the Gunners to United since Viv Anderson in 1987.
Emotions among the followers of these fierce rivals will be in sharp contrast today. Old Trafford will be floating on clouds of renewed optimism after a signing that sends out a series of threatening signals while Arsenal's fans will bemoan the loss of another pivotal figure after losing Cesc Fabregas and Samir Nasri last summer.
So what are the ramifications of Van Persie's impending switch for the club he is joining and the one he is leaving behind?
Arsenal manager Arsene Wenger will find it difficult to paint a pleasant picture after losing a player of such significance and influence. Despite the hopeful noises of one last season - and even the possibility of a new contract - Van Persie's career at The Emirates was dead from the moment he released what many regarded as a disrespectful statement outlining his intention to leave.
It is also a move which presents Wenger with one of his most formidable challenges. Arsenal's manager has not been able to win a trophy with Van Persie since the FA Cup in 2005 - so how difficult will he find it without him?
Arsenal fans may think Robin van Persie has turned his back on the club. Photo: Getty
And yet, despite the very obvious blow Van Persie's departure will deal to Arsenal, once the dust has settled and the pain of seeing him paraded in a Manchester United shirt has subsided, Wenger can still point to plenty of reasons for optimism.
Financially, the deal is a very good one for Arsenal. Irrespective of Van Persie's stature, to collect £24m for a player who could have walked away for nothing next summer represents sound business.
Wenger has also not waited for the Van Persie endgame to make his plans. This has been a summer with structure.
After what seemed the endless farewells for Nasri and Fabregas last summer, Wenger and Arsenal appeared slow to react and were reduced to trying to conclude a series of deals while watching the clock on transfer deadline day.
This summer Wenger has not repeated the mistake. He was making plans even before Van Persie confirmed Arsenal's worst fears by announcing he would not sign a new contract.
Germany's Lukas Podolski and France striker Olivier Giroud arrived from FC Cologne and Montpellier respectively, while the £15m acquisition of Spain's Santi Cazorla from Malaga has had most sound judges acknowledging a real coup for Wenger and Arsenal.
Wenger's confidence in his ability to renew Arsenal and finally claim that elusive trophy has never wavered, so he will point to the emerging talent of players such as Alex Oxlade-Chamberlain and hopefully the return to fitness of Jack Wilshere as further solid building blocks for an exciting future.
Thomas Vermaelen is a fine defender who commands the respect of his colleagues while Mikel Arteta brought craft and experience to midfield after his arrival from Everton.
So while no-one can dress up Van Persie's loss as good news for Arsenal or downsize the challenge now facing Wenger - especially as he has chosen Old Trafford as his next destination - cold reflection from their supporters may just leave them thinking life will go on.
For Ferguson and United, the capture of Van Persie represents a landmark moment in their own redevelopment.
Ever since Manchester City took the title in the closing seconds of last season, there has been little doubt Ferguson has been determined to send a message to the new champions, as well as anyone else looking for cracks in Old Trafford's edifice.
The signing of a player who has been arguably the Premier League's outstanding performer for the last 18 months does the job - especially as it is widely accepted that City manager Roberto Mancini would have loved to have to have added Van Persie to his own attacking riches.
It is also a signal that United can and will spend the big money on stellar stars when the moment arrives Ferguson can point at Van Persie as the flesh and blood embodiment of his insistence that owners the Glazers will support him financially when it matters, proof that his public support for the Americans is not simply lip service to his paymasters.
Ferguson will relish working with Van Persie and pairing him with Wayne Rooney - a partnership with the potential to deliver devastation on Premier League defences.
It may take time to come to fruition as Rooney occasionally does not take easily to a pairing, but they are of such quality that it is hard to see it not coming off.
England youngster Danny Welbeck may have mixed feelings on the matter having done so much to establish himself last season - but Ferguson will rotate his resources and Javier Hernandez will also come into the equation.
It should also be remembered Ferguson's greatest season, when the title, Champions League and FA Cup, was won in 1999, was done with an attacking quartet of Andrew Cole, Dwight Yorke, Teddy Sheringham and Ole Gunnar Solskjaer.
So Ferguson and United will parade the arrival of Van Persie as the day they showed the strength of their determination to fight back against the riches of Manchester City.
For Arsenal, there will be disappointment and undoubtedly a measure of bitterness. But it is also a new post-Van Persie era at The Emirates - and one with plenty to be hopeful about despite his leaving.