4.Nd5Developing another piece by B—Kt 5 or B 4 would be more in accordance with principle.
4…Be7There was a threat of Kt x B and Kt x P. If Black plays P—Q 3, the B must retire all the same after 5 B—Kt 5. It seems best to retire the B to K 2 rather than to B 4 or R 4, because there remains the threat of a pin subsequently by B—K Kt 5, which might become serious with the Knight at Q 5.
8…h6The K Kt is to support the advance of P—Q 4 subsequently, and that is why Black does not want to allow it to be pinned. This is sound strategy, since White has exchanged his Q Kt, which from B 3 prevents P—Q 4 in the ordinary way.
11.Bb3The first mistake. B—Q Kt 5 should be played to retard P—Q 4.
13.exd5The second mistake. Unimportant as it seems, it leads to the loss of the game. White did not defend the pawn by Q—B 2, because it would have proved 10 Q—Q 2 to have been a lost move. But giving up the centre is a far greater evil. Black now commands his Q 5 and K B 5, and this enables him to start an attack to which there is no defence. The game shows conclusively how important it is to maintain the centre.
16.Qe2to prevent P—K 5, which would now be countered by P x P and Q—B 4. However, as P—K 5 cannot be prevented permanently, and the Q must move in any case, Q—B 2 would have been the better move, as there the Queen cannot be molested by a Rook.
19…Rae8Black's game is beautifully developed, whilst White cannot make a combined effort. The Black Rooks are particularly well placed, and threaten to take an effective part in the attack in various ways. All this is the outcome of White losing the centre.
20.g3Though this prevents Kt (Q 4)—B 5, it weakens K B 3, which is all the more serious as Black threatens to open the file by P—B 5.
20…Qd7If now White refrains from taking the pawn, Black plays P—Q R 4 !
24…f4All the avenues of attack are now open, and White's game collapses quickly.
Edward Lasker, Chess Strategy (1921) · Public domain · source