It must always be a positive value. So we can still have a decrease in the entropy of the system. So this can still be a negative value as long as the increase in the entropy of the surroundings is greater than the decrease in the entropy of the system. So as long as this quantity is greater than this quantity, this will always be a positive value. This will always be greater than zero. Now, what we want to attempt to do in this lecture is to derive an equation by beginning with this equation and by using the definition of entropy, we want to derive an equation known as the Gibbs free energy.