Can anyone explain why, of all planets, Moon became the most significant influence in 16th-19th century medical advisories?

That is, the ephemerides of that era's almanacs were geared solely to moon positions and aspects; bloodletting and purging were timed by moon position; gelding cattle and weaning from the breast, too.

I also read that medieval almanacs were either "Great Almanacs" (charting all planets positions), or "Small Almanacs" charting only the Moon; and that it was the small variety that were most used for medical purposes, esp in the 17th-18th c.

Did the moon have special medical significance over and above the other planets?

Thanks,
Bill vV