In 1858, Paul Morphy was in the midst of his whirlwind tour of Europe, during which he would defeat nearly all of the greatest European players of the day. However, his most famous game came against two amateurs working together against the American.
The game in question happened during an opera (many say it was The Barber of Seville), attended by Morphy along with Duke Karl and Count Isouard in Paris. Morphy had White, with the consultants taking Black.
This was by far the most popular opening move of the 19th century, and remains extremely popular today. White stakes a claim to the center, while opening lines of development for his kingside bishop and queen.
1. ... e5
While Black has many good responses to 1. e4, this classical move is simple and effective. Black reestablishes symmetry, shows he plans to fight for the center, and opens lines for his pieces.
This is White's best and most logical try for an advantage with the second move. White develops a piece with a threat -- if Black does nothing, White can capture the pawn on e5. Thus, Black must respond, rather than beginning his own plans. White has also moved closer to castling, and continued to fight for control of the center.
2. ... d6
Black defends the e5 pawn with another pawn. This particular opening is known as the Philidor Defense. It is solid, but also passive -- which explains why it is rarely seen today. The e5 pawn is secure, but Black's kingside bishop is now hemmed in. More commonly, Black will develop a piece by playing 2. ... Nc6, which also defends the e5 pawn.
Morphy opens a fight for the center by creating tension between the pawns on d4 and e5. This also opens more lines for White's pieces -- this time, the queenside bishop has been activated.
3. ... Bg4
This brings us to the diagrammed position on the next page.