According to my collaborator Anthony Teth:
One must inhale before exhaling. The Devil represents this inhalation in a broad sense, denoting the accumulation of energy before action. Some tarot decks will interpret the card as representing bondage or servitude, but it should be known that the bondage in question is self-imposed and easily escaped. Constraints such as discipline or organization can be exceptionally beneficial when properly applied. Thus, the Devil represents the necessary winter rains preceding a glorious spring bloom.
Negative meanings can include bondage, ignorance, materialism and hopelessness.