The middle game presents the chess writer as well as player with the most formidable problems. Its theory is particulary difficulte to formulate, with the result that, as Dr Euwe explains, it has received less than adequate treatment in chess literature. The Middle Game was first conceived thiry years ago and required many years of intensive study by the former world champion and his collaborator, the Dutch international master Hans Kramer. Book One is devoted to what the authors call the "static features" of the middle game. The character of a position alters with every move ; it is the authors' purpose to identify those features of a given position which have more or less lasting properties and from them to assess its potentialities. The relative value of pieces, centre formations, closed, open and half-open formations, the struggle for open lines, weak pawns -- all are exhaustively studied, the illustrations coming entirely from master play.