Is it astronomy or astrology ? Is it superstition or common sense ? These are questions one should not overlook when pondering ancient writings. For example I recently ran across this
Melanchthon kept me a day at Schmalkalden with his godless and shabby astrology, because it was a new moon. Once he would not cross the Elbe [river] during a new moon. [Preserved Smith’s translation of ‘Table Talk’ (1915, page 202)]
On the surface one could get all bent out of shape over some medieval superstitious fellow refusing to cross a river due to moon phase. However, if you stop and think about it, the new moon is the darkest night of the month. The river in the 1500’s wasn’t exactly well lit and no doubt crossing the river on the darkest nights often resulted in tragedy. Thus the “superstition” of not crossing rivers on the new moon no doubt developed.