I personally don't believe trading can be compared to any of these professions.....or pretty much any profession for that matter. They all work under some sort of structure. There are laws for electricity, the human body is the human body, water and crap go down hill, etc. In these environments you solve a problem with static numbers. Trading is much too dynamic to put static numbers to it. The market is new every second, something not seen before. In trading everything works and nothing works.
Here is a good quote from Livermore.....
"Rarely do any of us grow up learning how to operate in an arena that allows for complete
freedom of creative expression, with no external structure to restrict it in any way. In the
trading environment, you will have to make up your own rules and then have the discipline
to abide by them.
The problem is, price movement is fluid, always in motion, quite unlike the highly
structured events that most of us are accustomed to. In the market environment, the
decisions that confront you are as endless as the price movements you intend to take
advantage of. You don't just have to decide to participate, you also have to decide when to
enter, how long to stay in, and under what conditions to get out.
There is no beginning, middle, or end - only what you create in your own mind."