421. From all this it can be seen how it is to be understood that charity and good works are distinct like willing well and doing well; that is to say, formally they are distinct, as the mind, which thinks and wills, is distinct from the body through which the mind speaks and acts; while essentially they are distinct because of the distinction in the mind itself which has an inner region that is spiritual, and an outer that is natural, as said above; so that when works proceed from the spiritual mind, they proceed from its good will, which is charity; but when they proceed from the natural mind, they proceed from a good will that is not charity. For even when it appears in the external form like charity, it is not charity in the internal form. In fact, charity in external form merely presents the show of charity, but does not possess its essence. This may be illustrated by a comparison with seeds in the ground. Each seed produces a plant, whether useful or useless, according to the nature of the seed. So is it with spiritual seed, which is the truth of the church derived from the Word; from this seed doctrine is formed, useful if from genuine truths, useless if from truths falsified. It is the same with charity that springs from good will, whether the good will is for the sake of self and the world or for the sake of the neighbor in a limited or in a broad sense; if for the sake of self and the world, it is spurious charity, but if for the sake of the neighbor, it is genuine charity. But of this more may be seen in the chapter on Faith, especially in the section where it is shown that charity is willing well, and good works are doing well from willing well (n. 374); and that charity and faith are only mental and perishable things unless they are determined to works and coexist in them when possible (n. 375-376).