Mercury in Sagittarius is in Mutual Reception to Jupiter in Gemini.Mercury is Quindecile Jupiter
So Jupiter and mercury are in mutual reception and they are aspecting each other via quindecile so this aspect is definitely highlighted in the discovery chart.
Quindeciles are powerful and this aspect could explain why jupiter has a strong passion and even obsession for accumulating knowledge.
Quindecile: Motivation and Determination
Ricki Reeves’ book Quindecile goes into depth about the interpretation of each planetary combination in this aspect. From what I’ve read, she seems to suggest that there is a compulsive feeling of “whatever it takes” to fulfill one’s motivation.
Quindecile to Jupiter: may suggest obsessive focus on education, philosophy or spirituality. This aspect may intensify the need for rewards in terms of Jupiter’s sign and house placement.
Quindecile to Mercury: the determined, obsessive or disruptive quality enters the mind in terms of the planet being aspected, potentially creating great anxiety. This extreme tension might become a fuel for intellectual output, and/or a cause for neurosis.
http://hniizato.com/quindecile-aspect/
It makes sense Jupiter is associated with higher learning bc if someone signs up to become a doctor this is many many years of education they must complete and you need the type of determination/motivation/obsession associated with a mercury quindecile jupiter in mutual reception to achieve this.