And so now what begins to happen is we have these Van Der Valley interactions. So London dispersion forces, which basically exist between the non polar molecule and the tails, the hydrocarbon tails of these phospholipids. So eventually, it moves across and makes its way back out on the other side. And once again, that salvation shell, that cage of water molecules, is basically reformed. Now, this discussion basically leads to the next important point. If a molecule is polar or it has some type of charge, what that means is it will not be very likely to actually pass across the cell membrane.