In Psalm 104:3, this signifies doctrine from the lowest, most basic divine truths. (Apocalypse Explained 594[10])

7407. 'And the frogs died out of the houses, out of the courtyards, and out of the fields' means that with those people reasonings arising from utter falsities, wherever they were present in the natural, came to an end. This is clear from the meaning of 'dying' as coming to an end; from the meaning of 'the frogs' as reasonings arising from utter falsities, dealt with above; from the meaning of 'the houses' as parts of the natural mind, dealt with above in 7397, at this point interior parts within it; from the meaning of 'the courtyards' as exterior parts of the natural mind (the natural has an interior and an exterior, see 3293, 3294, 4570, 5118, 5497, 5649); and from the meaning of 'the fields' as the more general and so even more exterior parts, since the fields are outside the houses and courtyards. Thus 'the frogs died out of the houses, out of the courtyards, and out of the fields' means that reasonings arising from utter falsities, wherever they existed in the natural, came to an end.