Known also as the Lord of the Gates of Matter and Child of the Forces of Time, the card of the Devil is aligned with Capricorn. Capricorn is goal oriented and once a goal is in sight, then this sign has the tenacity and stamina to pursue it. The sign of Capricorn, the Goat, has links with Pan, the Greek God of merriment, sensuality, fields and groves, spring and fertility.
When he appears in a reading, he indicates that we are caught in the grip of something, often an addiction, sometimes a habit that is hard to break. The card of the Devil often shows the Horned One holding a man and a woman in chains and this points to the nature of this card when we are hooked by habits and beliefs that are not so good for us. It's like we get stuck in a rut and don't know how to get out of it any more, and yet we can break the chains ourselves and indeed, we are the only ones who can. In fact, once we realise that the chains are of our own making, we can dissolve them.
This card not only represents habits that are hard to break, but it also represents that quality or feeling we all possess (or that possesses us!) from time to time and that is guilt. Guilt is one of the most insidious emotions and also one of the most useless and destructive. It is tied to the past but follows us into the present and also taints our future. It is something that we do to ourselves and it is a choice of focus - it signals where we have violated one of our values. Tied in with guilt is the emotion of shame - shame is similar to guilt, but shame is visited on us by others and is more tied to their values that they will convince you that you have violated. Again, this is something from the past that bleeds into the present and the future and really does not have any value - rather it is a means of control.
It is the quality of being in the grip of something that you feel you can't control - this is nonsense of course, you do have the power to control it, you just haven't realised it yet.
The best way to approach this card when it comes up in a reading is to learn to look at life more lightly - learn to laugh at yourself and at things that previously seemed so serious. When we are in the grip of The Devil we can lose our sense of humour and it is our sense of humour that separates us from the animal kingdom and makes us human.
Image from "Dragon Tarot - The Devil" by Alexandra ´Erkegris´ Alexandersson