The position is finally gaining independent value.
1. e2e4  1... e7e5  2. g1f3  2... b8c6  3. f1c4  3... f8c5  4. a2a4 In the open sea that is the theory of the Italian Opening, this move is a breath of fresh air, albeit a small one, since the positions are so similar that only those who have studied dozens of hours can begin to understand the subtle differences. In my database, this is only the 13th most popular move. To give you an idea, even 4.Bxf7+ has more games played (although I didn't check for double games or games played on blitz; that would be too much). 4... g8f6  5. d2d3 As I wrote before, 4.a4 is a very small breath of fresh air. After 5.d3 we're back to hundreds of games, although this is better than the customary thousands. To be fair, many transpositions are still possible. 5... d7d6  6. a4a5 Following the principle, Whoever says A must say B. Or, paraphrasing it: If you play a4, you must play a5.