In the Bible, things that are lower down, or under, physically, generally represent things that are lower or more external spiritually. In some cases, the lower things have been separated and put away to protect the good, but in others, it can mean that a less exalted idea or good desire is supporting a more exalted one.

(Referenser: Arcana Coelestia 4564 [1-2], 8610, 9656)

8609. 'And they took a stone' means the lowest level of God's truth. This is clear from the meaning of 'a stone' as truth, 643, 1298, 3720, 3769, 3771, 3789, 3798, 6426, in this instance the lowest level of truth since it was put underneath him and he sat on it. An ordinary stone furthermore means a lower level of truth, while a precious stone means a higher or more internal level of truth. What the lowest level of truth is becomes clear from what has been stated above in 8603 about the levels of truth that follow one another in order; that is to say, there are interior truths and exterior truths, the lowest of which are meant by the lowest level of truth.