The essential ingredient is the Moon's Nodes. These are the meeting point of the apparent path around the earth of the Sun, and the path around the earth of the Moon. Imagine them as two hoops or rings of the same size, fitted within one another and tilted at an angle. The two points where the two hoops meet are the North Node and the South Node. I wrote a little about nodes about two years ago in Astrobods, but as many members will have joined since then I hope you'll forgive the repetition.
Nodes have a special place in astrology and particularly in spiritual astrology.
I call them spirit doors and see them as gateways bringing to us from the South Node our karmic experiences from earlier existences, and leading us towards the North Node - our spiritual destiny. In a birth chart they can reveal a lot about our past karmic lessons and those that we bring with us. We can see where things come easily to us but which need to be left behind - and the spiritual reason as to why we have incarnated at this particular place and time. They connect us to who and what we really are, our purpose and spiritual focus. Nodes too have their cycle, they move slowly backwards through the constellations, taking approximately 18 years to return to their starting point.