In most cases two centre squares become inaccessible at once,
through the opponent placing one of his pawns in the centre;
therefore it would seem a good plan to lure that pawn away, and
this is rendered feasible by playing P-K4 or P-QB4 when the
opponent has a pawn on his Q4, and P-Q4 or P-KB4 when he has a
pawn on K4. In the following we will consider such manoeuvres as
could apply either to White or Black, from the point of view of
White, to whom the initiative is, as pointed out above, a sort of
birth-right. Naturally, should White lose a move, as, for
instance, 1. P-K4, P-K4; 2. Kt-KB3, Kt-QB3; 3. P-QR3? the
position is reversed, and Black is bound to obtain the initiative
which is White's birthright.

The pawn moves mentioned above also have the tendency of giving
the Rooks an opportunity for action. A Rook standing behind an
advanced pawn may support its further advance, or, if the pawn
should be exchanged, might get an open file.

The damage we wish to inflict on our opponent we must, of course,
try to avoid ourselves. Thus we will not easily give up a centre
pawn unless we can obtain some other advantage in doing so. This
advantage may be, that in exchanging the centre pawn we open up
lines of attack for our pieces, or that we are able to place one
of our pieces in a commanding position in the centre of the
board.

The following example may serve as an illustration. Supposing
White plays after