jack

Jack of all trades and master of none. A term of contempt for someone who tries anything and everything but is not an expert in any one field.
~ Brewer's Dictionary of Phrase and Fable ~

The phrase "jack of all trades" is a curious thing. Some people wear the badge with pride, confident in the value of the breadth of their knowledge and that what they don't know they can work out or at least fake, that they can bring together all of these pieces of knowledge to create a greater whole. Like a polymath or "Renaissance man". Some aim the title at other people like an accusation: "Jack of all trades, master of none". One of reasons Plato places so little value on mimetic artists in his Republic was that, by virtue of their art, they need to know a little about everything and are thus prevented from becoming experts in any one topic by the necessary breadth of their knowledge.

But its the original aphorism that catches my attention:

Jack of all trades, master of none, though ofttimes better than master of one.

Seems like each time someone abbreviates the original proverb, it's an attempt to alter the meaning of it. "Jack of all trades" has a relatively positive, if roguish, ring to it. Adding "master of none", reverses that reading of it entirely, making it contemptuous and mocking, emphasising a failure to reach real status or knowledge. But the original phrase balances both sides. It acknowledges the potential and the possible value of that broad, if not highly in-depth, knowledge, while not downplaying the value of the opposite approach of depth of knowledge in a narrow field.

And while I'm vaguely on the topic, what is it about the name 'Jack' that so strongly suggests the rogue? Or is this just a me thing?