Well, over time, we're going to get the following case in which we're going to have equal amounts of molecule A on both sides and equal amounts of molecule B on both sides. Basically, as a result of Brownian motion, molecules A and molecules B will be in a constant state of motion. And based on the law of entropy, the most mathematically probable state of our system is in which we have an even amount of molecules on each side. 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.