18 But especially mark this, how very pointedly Paul says, For this corruptible must put on incorruption, and this mortal must put on immortality. For this body shall be raised not remaining weak as now; but raised the very same body, though by putting on incorruption it shall be fashioned anew —as iron blending with fire becomes fire, or rather as He knows how, the Lord who raises us. This body therefore shall be raised, but it shall abide not such as it now is, but an eternal body; no longer needing for its life such nourishment as now, nor stairs for its ascent, for it shall be made spiritual, a marvellous thing, such as we cannot worthily speak of. Then, it is said, shall the righteous shine forth as the sun, and the moon, and as the brightness of the firmament. And God, fore-knowing men's unbelief, has given to little worms in the summer to dart beams of light from their body, that from what is seen, that which is looked for might be believed; for He who gives in part is able to give the whole also, and He who made the worm radiant with light, will much more illuminate a righteous man.
Source: Catechetical Lectures (New Advent)