So this is the most probable state. And if we begin with state number one, where we have all the A molecules on the left side, all the B molecules on the right side, eventually we will develop the following state. So we say that molecule A moves down the concentration gradient from a higher concentration to a lower concentration. So notice we had no molecules A on the right side. And so A will move naturally from this location to this location. And likewise the B molecules will move down their concentration gradient from a higher concentration to a lower concentration in the opposite direction of A.