1] _Concentration and Isolation_ .-- The value of "concentration" is often insisted on, but the author desires to call attention to a misunderstanding on this point, to which he called attention in an essay in 1905.

To the author, it seems that concentration is a means and not an end, and that the end is what he called "isolation" in the essay.

If a man concentrates his mind on any subject, the advantage he gains is that he prevents other subjects from obstructing the application of his mental powers to that subject; he pushes to one side and isolates all other subjects.

In this particular activity it does not matter whether we call his act "concentration" or "isolation" because the whole operation goes on inside of his own skull, and concentration on one subject automatically produces isolation or elimination of all others.
But when concentration is attempted on external objects, the case is very different, for concentration may not produce isolation at all.

For instance, if 4 ships in column _A_ concentrate their fire on the leading ship in column _B_, the other 3 ships in column _B_ are not isolated, and can fire on the ships of column _A_, even more effectively than if column _A_ was not concentrated on the leading ship of _B_, because they are undisturbed by being fired at.