There are some things which spirits most especially shrink from, as when anything like sharp, pointed articles were imaged in my mind, immediately then, as if aroused, they would start to make trouble. I believe this was due to the fact that things of this nature cannot be conveyed and portrayed to the angels; for earthly figures are those that are comparatively sharp, while heavenly forms begin from what is circular. There are certain kinds of animals also which they very much abhor for the same reason, such as those, I suppose - I am still not sure about this - which are forbidden in the books of Moses and considered as profane.