Mud in a dream commonly reflects the sense of being stuck -- progress that's slowed to a crawl, or effort that doesn't seem to be moving you anywhere. Struggling to pull your feet free can mirror real frustration with a situation that resists quick resolution, however hard you're actually working at it.
The Artist must know how to vary the planets significations according to the year wherein he writes, having still a regard to the grand Epoch of superior Conjunctions or Comets preceding. - William Lilly (1602.-1681.)