This song has an interesting inspiration. Paul wrote it for Lennon's son "Julian". It initially went, "Hey Jules.. don't make it bad". After he found out that John was having an affair with Yoko Ono, and his marriage was going to fall apart, he drove over to visit Julian and Lennon's ex-wife, and wrote the song on his way over.
This is one of my favourite Paul songs at the moment:
http://youtube.com/watch?v=YHBKAyn17vwThe linked video is also allegedly the first music video ever made. They tended to be the first to do everything
.
Anyways, this was Paul's answer to "Strawberry Fields Forever". I really like the solo at 1:09.
(The whole group made contributions to both songs though).