Sagittarius, the ninth sign of the Zodiac, is masculine and mutable fire, representing the blending of physical strength, energy and powerful intellect. It was the Egyptian sign of war, the time of year when the armies marched and generals laid plans for conquest.  In the northern hemisphere, Sagittarius appears during the time when the hours of darkness are lengthening, at time when winter is ushering the harsher elements of cold and snow and ice.  Native Americans regarded it as a time for quiet reflection, as well as a time to sit around the campfires and recount tribal and family histories that were handed down from one generation to the next.  It is also a time for philosophical discussion and enhancement, a time when mental activities (indoors, sheltered, by the hearth fire) are more active than physical activities (outdoors, exposed to the elements, pressed by needs to prepare for the winter). It is a time to sit back and relax and get in touch with the spirtual and intellectual side of self again.

Sagittarius is ruled by Jupiter, which blesses with an ability to see the overall situation of things.  The Sagittarian mission in life is to gain control over body and mind, bringing them together to work in conjuction.  There is a natural need for diversity in ideas and actions, leaving the Sagittarian who stagnates intellectually or physically in a state of discontent.  That discontent, left to fester leads to depression, a very unnatural state for a Jupiter influence.  In the body, Sagittarius rules the thighs and the liver and when in a state of discontent or depression, the health of the liver can be directly affected.

Chiron, the centaur, and half-brother of Jupiter (Saturn fathered them both), is most directly related to Saggitarius. Hercules, drunk and showing off for his companions, shot an arrow aimlessless for distance, and mistakenly shot his beloved teacher and friend, Chiron.  The poisoned arrow punctured Chiron's thigh and brought him to the point of death, but being immortal, he could not pass over into the realm of the dead.  As time passed, Chiron became depressed over his painful existence froun ght would that could not heal, and he devised a plan by which he would end his suffering.  Prometheus, who gave the gift of fire (enlightenment) to mankind, had angered Zeus beyond reason for that action.  Zeus had him imprisoned in chains and thinking he had sealed Prometheus's fate forever, sealed his sentence with the stipulation that Prometheus could not be freed until a god or goddess would willingly surrender their life for him to be set free.  Chiron made that sacrifice, Prometheus was set free and enlightenment, once again, came to mankind.  Chiron was a healer, teacher and philosopher, the prototype for Jesus in Christian mythology.  When Chiron gave up his life and died, Zeus placed him in the heavens as the constellation Sagittarius.

The Jupiter effect on Sagittairans tends to be through their desire to avoid commitment. Jupiter spent a good deal of his time ignoring his responsibilities on Olympus in favor of amorous pursuits among mortals. Saggitarians tend to favor open relationships where they have a ready escape should things get too hot or too complicated for them.  Other placements must be taken into account when determining how a Sag native will deal with commitments such as marriage or business partnerships.

The goddess Artemis (Diana) is also closely associated with the Sagittarian archetype.  Goddess of the hunt and associtated with the new moon, it is her influence that brings the Sagittarian athletic prowess and love of sports.  Her influence is strongest in the Sagittarian need for personal freedom, love of the outdoors and athe desire to live apart from the chaos of communal living.  Modern day Sagittarians, like ancient Chiron, need to spend time in retreat, learning, comtemplating and rejuvenating.  Like him, they also need to share what they learn or experience.

Sources:

Bullfinch's Mythology:Age of Fable  by  Thomas Bulfinch

Mythic Astrology, Archetypal Powers in the Horoscope  by  Ariel Guttman & Kenneth Johnson