"But this is only a figure."
True. But is the reality intended, less or more than the figure? Does not the rust and the moth mean more than disease? And does not the heart mean more than the heart? Does it not mean a deeper heart, the heart of your own self, not of your body? of the self that suffers, not pain, but misery? of the self whose end is not comfort, or enjoyment, but blessedness, yea, ecstasy? a heart which is the inmost chamber wherein springs the divine fountain of your being? a heart which God regards, though you may never have known its existence, not even when its writhings under the gnawing of the moth and the slow fire of the rust have communicated a dull pain to that outer heart which sends the blood to its appointed course through your body? If God sees that heart corroded with the rust of cares, riddled into caverns and films by the worms of ambition and greed, then your heart is as God sees it, for God sees things as they are. And one day you will be compelled to see, nay, to feel your heart as God sees it; and to know that the cankered thing which you have within you, a prey to the vilest of diseases, is indeed the centre of your being, your very heart.
MacDonald, George; eBook-Ventures (2010-08-07). Unspoken Sermons - Series 1, 2 & 3 (pp. 72-73). Unknown. Kindle Edition.