Some time ago I guest-lectured to some undergrads in a science curriculum track about environmental advocacy. I said I had read somewhere that a scientist is a feather and the evidence is the wind - the scientist makes no effort to control the evidence but just floats wherever it takes her. Obviously this is an incomplete construct that ignores hypothesis formation etc., but is supposed to represent the ideal of how a scientist reacts to evidence.
The advocate isn't a feather, neutral as to where the wind blow. I didn't have a good analogy then for an environmental advocate/lawyer, but now I think the advocate is a sail and the evidence is the wind - how and where it blows is critical, but you have a role as well in where you're going. I also like the sail analogy instead of a sailor, retaining the ideal that the lawyer is a tool of the client/sailor (ideally) and isn't in charge of the ship.
What the sail analogy doesn't capture is the idea that legal contests are pattern-fitting contests. One side says the present facts and law fit that side's represented pattern of facts and law, while the other side presents different patterns.
Still working it out.