In Job 40:15, the behemoth signifies the natural man as to the goods called delights of natural love. (Apocalypse Explained 455[18])

"Behemoth" has the same meaning as "beast" in the Word, namely, the natural affections that belong to man. Therefore it is said, "behold, the Behemoth, which I have made with thee." His spiritual pasture is true knowledge; this is meant by "he eats grass like an ox." (Apocalypse Explained 507)

(References: Apocalypse Explained 455)