"The idea of this defence, introduce by Philidor (1749), is to protect the advanced King's Pawn from the adverse Knight before proceeding with Greco's Counter Gambit, [f5]. The second player limits the action of his King's Bishop and submits to a cramped position in the hope of establishing a strong center of Pawns. The first player, however, having the move, commences an attack on his own account by [3.d4], or [3.Bc4] (threatening [4.Ng5]). Against the latter [f5] is unsatisfactory, as was proved by Allgaier in 1795 (Note 1, Col. 6). Cols. 1-9 show the consequences if Black disregards his opponent's move [3.d4]. "The weakness of the Philidor," says Mr. Potter (1885), "consist in the fact that [exd4] being apparently incumbent on Black, whereby all his means of development become paralyzed. Could that capture be rendered unnecessary his development though slow would be assured, and the future of the game would be such as skill, hand in hand with patience, might hopefully face." Cols. 8-10 give various trials, showing on the whole that, as Mr. Potter adds, the inferiority which results is not very pronounced. He has demonstrated in Land and Water that the line of play given in Col. 8 permits numerous variations, from which we may conclude that it has not yet reached its final form." --Chess Openings, Ancient and Modern; 1889
The bracketed and bolded moves are simply transcriptions from descriptive notation to algebraic.
Interesting line from an old book for the Philidor. The ideas are mostly sounded and the lines are not fully optimized for white. For example, bringing the bishop back to the center when threatened by the pawn narrows its scope rather than dropping it back to b3. However, this might have been because of the flavor of the era and some of Steinitz's dogmatic views on the center and bishop placement.
The book I retrieved this from is a free book in google's library, for those who are interested in some older chess opening theory. :)














