Among other things already mentioned, the Devil can go one of two ways--either a need to be more down to earth, or more sensual--or too much of earthiness or sensuality (depending on its dignity).
Capricorn is ruled by Saturn, which is about limitations, responsibility and Karma. Hedonism may be encouraged, but not without an understanding of the inherent responsibilities and consequences.
On the other hand, it tells the person who is so spiritual they have their head in the clouds all the time that life on earth means one must have a concern for earthly things. The lessons of this life are learned here in this body, on this earth.
Nevada
P.S. The interesting thing to me personally about this card is that because it's a Capricorn card I associate it with my dad, and he's the one who would bring me down to earth when I was daydreaming too much, when I was a child. My mom, a Pisces and an artist, taught me about dreams and imagination. My dad taught me to apply these things in practical ways.