Chapter XXII. Of the fourfold method of discrimination. This power of discriminating will then be necessary for us in the fourfold manner of which we have spoken; viz., first that the material does not escape our notice whether it be of true or of painted gold: secondly, that those thoughts which falsely promise works of religion should be rejected by us as forged and counterfeit coins, as they are those which are not rightly stamped, and which bear an untrue image of the king; and that we may be able in the same way to detect those which in the case of the precious gold of Scripture, by means of a false and heretical meaning, show the image not of the true king but of an usurper; and that we refuse those whose weight and value the rust of vanity has depreciated and not allowed to pass in the scales of the fathers, as coins that are too light, and are false and weigh too little; so that we may not incur that which we are warned by the Lord’s command to avoid with all our power, and lose the value and reward of all our labour. “Lay not up for yourselves treasures on the earth, where rust and moth corrupt and where thieves break through and steal.” 1158 For whenever we do anything with a view to human glory we know that we are, as the Lord says, laying up for ourselves treasure on earth, and that consequently being as it were hidden in the ground and buried in the earth it must be destroyed by sundry demons or consumed by the biting rust of vain glory, or devoured by the moths of pride so as to contribute nothing to the use and profits of the man who has hidden it. We should then constantly search all the inner chambers of our hearts, and trace out the footsteps of whatever enters into them with the closest investigation lest haply some beast, if I may say so, relating to the understanding, either lion or dragon, passing through has furtively left the dangerous marks of his track, which will show to others the way of access into the secret recesses of the heart, owing to a carelessness about our thoughts. And so daily and hourly turning up the ground of our heart with the gospel plough, i.e., the constant recollection of the Lord’s cross, we shall manage to stamp out or extirpate from our hearts the lairs of noxious beasts and the lurking places of poisonous serpents. 1158     S. Matt. vi. 19 .