Wanna hear my theory about the whole 'Paul Is Dead' thing? No? Too bad, here it is!
In this theory Paul did NOT die, and the Beatles did NOT deliberately insert clues into their albums. So how does one explain this phenomena? Coincidence? I think not!
It's funny that the date of Paul's supposed death (1966) corresponds roughly with the time that the Beatles (George and John at least) began using LSD. A well documented side-effect of taking LSD (particularly in the prodigiously huge doses that people were taking at the time) is that the LSD user experiences ego death and rebirth.
To quote from Timothy Leary's 1960s Acid Manual based on the Tibetan Book of the Dead (upon which Lennon based the lyrics for 'Tomorrow Never Knows'):
O (name of voyager),
That which is called ego-death is coming to you.
This is now the hour of death and rebirth.
Take advantage of this temporary death to obtain the perfect state -
(from First Bardo Instructions, page 115 of the 1995 edition)
So what's this have to do with anything? Well, despite the fact that McCartney was the Beatle who (after finally taking LSD in 1967) revealed to the press that he had done so, he didn't get into the LSD experience as much as the others. He has stated in interviews that he had heard that if you take LSD too many times it irrevocably changes you, so he used it a handful of times and that was it.
So this evidence suggests that, unlike the other Beatles, Paul McCartney was a very cautious user of LSD, and didn't submit to going 'all the way' to the experience of ego death (which itself requires a heavy dose to achieve).
So the irony is that McCartney is the only Beatle NOT to have died on LSD!
So what about the hundreds of well-documented 'clues' that suggest that Paul Is Dead? Here my theory gets a little strange, so bear with me. I see it as a manifestation of cosmic humour, synchronicity rather than coincidence. Strange things can happen when massive amounts of energy are unleashed, such as they were in the 1960s when the acid fad was at its height. In a way the 'clues' were an expression of the energy of the universe (operating on the chaotic principles of self-organisation) poking fun at McCartney for keeping his ego intact instead of experiencing the oneness with everything that so profoundly affected the other Beatles.
So that's my theory, my theory that it is. The truth is out there, eh?
If these shadows have offended, think but this and all is mended.. Don't get upset! Take it in the spirit in which it was intended.
It's all a BIG JOKE