Even for a club the size of Manchester United, it's not enough just to want a player. The player has got to want it, too.
If not, you're just a kid staring through the window of a sweets shop without the money to buy anything.
It's easy to see why United might want to sign Ross Barkley. He's a young, English, creative midfielder. Like Wayne Rooney, Chris Smalling and Phil Jones before him, he ticks the boxes for a model United signing.
Above all, though, he's a midfielder. A central midfielder. Which makes him worth his weight in gold at Old Trafford.
But while Barkley would fill a desperate need at United, the bigger question is whether he needs United. And the answer, at the moment at least, is no.
He's playing for a team sat happily in the Premier League's top four heading into the new year.
But more than that, he's playing.
David Moyes, his manager at Goodison Park, will say that his management of Barkley helped his rise, that the odd game for Everton and the experience in the Championship helped him make the breakthrough this season.
And while he would be right in that assessment, there's no escaping the fact that it is Roberto Martinez who has made the 20-year-old central to his plans.
It didn't take the Spaniard long to realise the talent he had after making the move from Wigan in the summer.
Barkley started the first game of the season at Norwich, scoring his first Premier League goal in a 2-2 draw. So far, he has figured in 18 of Everton's 19 Premier League games, starting 14.
He's kept Leon Osman, a veteran of more than 300 Premier League appearances, out of the team, and there are few Everton fans pining for the return of Marouane Fellaini.
He has won his first England caps and, injury permitting, should be on the plane to Brazil in the summer.
Trusted by the manager of the club he's been at since he was 11, performing in a team that is playing well and earning recognition at international level, life is good for Barkley. Very good.
So good, in fact, that it's difficult to see why he would want to leave, especially halfway through his first season as a regular.
One day, that might change. Barkley might feel he needs a new challenge or that Everton can't match his ambition to win things, the Premier League or maybe the Champions League. If and when that time comes, he may well consider an offer from Old Trafford.
A move to United would allow him to stay in the Northwest and, without trying to predict the future, challenge for trophies.
But you suspect if Barkley is to move in January, it will not only take a huge bid, but also a hard sell from Moyes.
After all, as it stands, United need Barkley more than he needs them.