Today I'm going to explain a simple but essential concept in the end. The idea of the Principle of two weaknesses is that often, our opponent can be able to defend a single weakness very well, and creating a second can break his position. But what would be a weakness? We can define here that it is something that our opponent needs to worry about: Material advantage, an open file, a weak square, weak pawn, etc.The example below is very well known. Thinking about this idea, how would you play white?