"Jack of all trades the master of none"

It refers to someone who is kind of good at a variety of disciplines but has not mastered any of them.

The correct form of the proverb is "A jack of all trades is master of none".

It means that somebody who has drifted from one occupation to another and picked up a bit of many different skills won't have mastered any of them properly.

That's interesting, syntinen.

Also, The Proof of the Pudding is in the eating, not the proof is in the pudding. I love these things.