I acquired as much experience from those imaginary cases as I should from real ones, and in addition, I learned a method which is the one that I practise to this day." "Do you mean that you still invent imaginary cases as mental exercises ?" "No; I mean that, when I have a problem of any intricacy, I invent a case which fits the facts and the assumed motives of one of the parties.
Then I work at that case until I find whether it leads to elucidation or to some fundamental disagreement.

In the latter case I reject it and begin the process over again." "Doesn't that method sometimes involve a good deal of wasted time and energy ?" I asked.
"No; because each time that you fail to establish a given case, you exclude a particular explanation of the facts and narrow down the field of inquiry.

By repeating the process, you are bound, in the end, to arrive at an imaginary case which fits all the facts.

Then your imaginary case is the real case and the problem is solved.

Let me recommend you to give the method a trial." I promised to do so, though with no very lively expectations as to the result, and with this, the subject was allowed, for the present, to drop..