no Pawn move should be made which is not absolutely necessary to
open a line for a piece; or, no piece should move twice as long
as there are pieces which have not yet moved at all; or, no piece
should be developed to a square from which the opponent can drive
it away at the same time furthering his own development; or, the
right of castling should not be foregone by moving the King or by
any other way, as castling develops a Rook and places the King in
safety with one move while more moves are required to the same
end if castling is not possible, and so on.

The beginner who makes this great principle of development quite
clear to himself has made the most difficult step on the way to
mastership. The grasp of the far reaching influence of the
mobility of the pieces in the opening upon the further
development of the whole game is really what distinguishes the
master from the average player.

Of course, it would be too difficult for the beginner to find out
for himself what squares are the most favorable for the different
pieces; at any rate, it would take him a long time to gain that
knowledge by experience. Fortunately, the experience of the
masters of several generations is accessible to us and so it is
possible to expedite considerably the process by which the mind
of the student is adapted to the tactics required in every game
of Chess to carry out the principle of speedy development. To a
great extent these tactics, too, can be simply explained from the
point of view of giving the pieces their utmost mobility so that
they will be readily understood by the reader who has followed
the arguments given in the foregoing pages.