In vedic astrology sun in sagittarius can make one preacher or teacher. Those people feel that they have all the knowledge and wisdom of the world. They love to guide others with their divine knowledge and most of them love to be university professors if sun is well placed. The person sometimes feel overconfident about knowledge.
If jupiter is exalted in cancer, the person stays humble in terms of knowledge. Sun in sagittarius shows that the individual follows the guidance of gurus, teachers and father. The quality of preaching depends on the position of jupiter. If jupiter is well placed, the person will gain good knowledge and will give proper guidance. Sun is ego and Sun in sagittarius shows that ego is developed through gain of knowledge. They are law abiding and religious too. If jupiter is not well placed than father become very strict of religion and the person may be manipulative in terms of gaining and sharing knowledge.
In vedic astrology, each planet is controlled by nakshatra. Sun in mula nakshatra is controlled by the position of ketu, sun in purvaphalguni nakshatra will be controlled by the position of venus and sun in uttarphalguni nakshatra will be controlled by itself.
Before analysing the position of sun, the position of jupiter must be taken into consideration.