Centiloquium of Hermes Trismegistus (1262):
"The North Node with the infortunes denotes terrible mischiefs, for he increases their malice; but with the fortunes he works good, and augments their benignity. But the significations of the Dragon's tail are to be noted the contrary way."
Guido Bonatti (1296-1300 CE).
“Indeed, the Head of the Dragon is naturally a benefic, and of a masculine nature; but by accident it is sometimes a malefic. For its nature is composed of the nature of Jupiter and of the nature of Venus, and this signifies increase … Indeed its Tail is naturally malefic, and of a feminine nature; but if by accident it sometimes becomes a benefic. And its nature is composed of the nature of Saturn and Mars. And it signifies decrease, namely dejection and a fall and poverty, and the decrease of every good thing and every fortune.”
Later, the concepts of fate, karma and reincarnation became associated with the nodes. In this view, the south node represents the past and the north node represents this life or what the person should be striving toward. On Molly's Astrology Blog is a good example of the karmic interpretation: "In a karmic sense, the Moon’s Nodes represent lessons to be learned in this Earthly incarnation. These lessons almost always have to do with the way we connect with others."
Personally, I seldom use the Nodes in interpretation unless they are within 2 degrees of being conjunct another planet or in a partill aspect. I treat them as a unity, not that you are moving from the South Node to the North node or focusing on one over the other. Always in opposition, they continually present us with the challenge of shining a light on our basic approach to life, our habits and unconscious patterns. How do you use the Nodes? Do you find them useful?