There is an alleged "true story" about Winston Churchill and Alexander Fleming that is often circulated via e-mail. It is in fact a popular myth. The value of that story diminishes if it is a concocted one.
On the other hand, there are other popularly misquoted items that are worth reading anyway. The following is widely circulated even by many authoritative sources as written by US President Abraham Lincoln to his son's teacher. I find it touching, even after knowing that he did not.
Letter to Son's Teacher
He will have to learn, I know, that all men are not just, all men are not true.
But teach him that for every scoundrel there is a hero,
that for every selfish politician there is a dedicated leader.
Teach him that for every enemy, there is a friend.
It will take time, I know but teach him if you can,
that a dollar earned is of far more value than five found.
Teach him to learn to lose and also to enjoy winning.
Steer him away from envy if you can, teach him the secret of quiet laughter.
Let him learn early that the bullies are the easiest to lick.
Teach him if you can the wonder of books,
In school teach him it is far more honourable to fail than to cheat.
Teach him to have faith in his own ideas, even if every one tells him they are wrong.
Teach him if you can, how to laugh when he is sad.
Teach him there is no shame in tears.
Teach him to scoff at cynics and to beware of too much sweetness.
Teach him to sell his brawn and brain to the highest bidders
but never to put a price tag on his heart and soul.
Teach him to close his ears to a howling mob and to stand and fight if he thinks he is right.
Treat him gently, but do not cuddle him,
because only the test of fire makes fine steel.
Let him have the courage to be impatient.
Teach him always to have sublime faith in himself,
because then he will always have sublime faith in mankind.
This is a big order, but see what you can do.
He is such a fine little fellow, my son.