Chapter XXXIX. That deep things ought not to be preached at all to weak souls. But the preacher should know how to avoid drawing the mind of his hearer beyond its strength, lest, so to speak, the string of the soul, when stretched more than it can bear, should be broken.  For all deep things should be covered up before a multitude of hearers, and scarcely opened to a few.  For hence the Truth in person says, Who, thinkest thou, is the faithful and wise steward, whom his Lord has appointed over his household, to give them their measure of wheat in due season? ( Luke xii. 42 ).  Now by a measure of wheat is expressed a portion of the Word, lest, when anything is given to a narrow heart beyond its capacity, it be spilt.  Hence Paul says, I could not speak unto you as unto spiritual, but as unto carnal.  As it were to babes in Christ, I have given you milk to drink, and not meat ( 1 Cor. iii. 1, 2 ).  Hence Moses, when he comes on from the sanctuary of God , veils his shining face before the people; because in truth He shews not to multitudes the secrets of inmost brightness ( Exod. xxxiv. 33, 35 ).  Hence it is enjoined on him by the Divine voice that if any one should dig a cistern, and not cover it, and an ox or ass should fall into it, he should pay the price ( Exod. xxi. 33, 34 ), because when one who has arrived at the deep streams of knowledge covers them not up before the brutish hearts of his hearers, he is adjudged as liable to penalty, if through his words a soul, whether clean or unclean, be caught on a stumbling-stone.  Hence it is said to the blessed Job, Who hath given understanding unto the cock? ( Job xxxviii. 36 ).  For a holy preacher, crying aloud in time of darkness, is as the cock crowing in the night, when he says, It is even now the hour for us to arise from sleep ( Rom. xiii. 11 ).  And again, Awake ye righteous, and sin not ( 1 Cor. xv. 34 ).  But the cock is wont to utter loud chants in the deeper hours of the night; but, when the time of morning is already at hand, he frames small and slender tones; because, in fact, he who preaches aright cries aloud plainly to hearts that are still in the dark, and shews them nothing of hidden mysteries, that they may then hear the more subtle teachings concerning heavenly things, when they draw nigh to the light of truth.