The reason is that no one can see the spiritual sense, except only if it is granted him by the Lord, and if he is in possession of Divine truths given by the Lord. For the spiritual sense of the Word is solely concerned with the Lord and His kingdom. That is the sense known to His angels in heaven, since it contains His Divine truth. A person who knows the science of correspondences, and wants to use his own intelligence to explore the spiritual sense of the Word, can do violence to this Divine truth. For a knowledge of a few correspondences will enable him to corrupt that sense, and even misapply it to proving false propositions. This would be to do violence to Divine truth, and thus to heaven where that truth resides. Therefore if anyone wishes to lay bare that sense, relying on himself instead of on the Lord, heaven is closed to him, and this results in his being unable to see any truth at all, or becoming spiritually deranged.

Another reason is that the Lord teaches every person by means of the Word, and uses in teaching the knowledge he already has, rather than directly implanting new knowledge. Therefore, if a person is not in possession of Divine truths, or only a few truths accompanied by false notions, he can use these to falsify the truths. This too is what all heretics do with the literal sense of the Word. So to prevent anyone coming into possession of the spiritual sense and perverting genuine truth, the Lord has established guards, who are meant by the cherubim in the Word.