Guru and Shani: the two great teachers
Guru (Jupiter) and Shani (Saturn) are the two great teachers of the classical texts. Jupiter brings expansion, wisdom and grace, and Saturn brings discipline, limits and endurance.
What it is
Jupiter is a benefic and the karaka of dharma. Saturn is a malefic in the standard scheme and is central to the Sade Sati rule. Their paired reading is common in the texts.
How it is worked out or read
The contrast is a reading tool, not a verdict. Both are discussed in their own articles.
Where it appears on this site
Two slow grahas
Jupiter and Saturn are the two slowest of the visible grahas, and their long cycles give them a special role in timing. Jupiter takes about twelve years to go round the zodiac, spending roughly a year in each sign. Saturn takes about twenty-nine and a half years, spending roughly two and a half years in each sign. Because of this slow pace, their transits are used to describe the broad seasons of a life rather than its daily weather.
Jupiter, Guru, is read as the graha of wisdom, teaching, faith, children and expansion. Saturn, Shani, is read as the graha of discipline, time, labour, endurance and limitation. One is the teacher who opens doors; the other is the taskmaster who makes the work real.
Dignities and friendships
Jupiter rules Dhanu and Meena, is exalted in Karka and debilitated in Makara. Saturn rules Makara and Kumbha, is exalted in Tula and debilitated in Mesha. Notice that Jupiter falls in the very sign Saturn rules, Makara, a pairing that teachers sometimes use to show the contrast between the two natures.
In the Parashari table, Jupiter counts the Sun, Moon and Mars as friends, Mercury and Venus as enemies, and Saturn as neutral. Saturn counts Mercury and Venus as friends, the Sun, Moon and Mars as enemies, and Jupiter as neutral. So the two are neutral towards each other, and their friendships run in almost exactly opposite directions.
Aspects and dashas
Both grahas have special aspects. Jupiter aspects the fifth, seventh and ninth houses from itself; Saturn aspects the third, seventh and tenth. Jupiter's aspects are traditionally read as protective and supportive, and Saturn's as testing and slowing. In the Vimshottari scheme, Jupiter rules sixteen years and Saturn nineteen, and the two mahadashas follow each other: Jupiter's period is followed directly by Saturn's. Many people therefore live through a long stretch of thirty-five years governed by these two in turn.
Their conjunction, which happens roughly every twenty years, was used in older traditions as a marker of broad historical periods, though that use belongs more to mundane astrology than to the reading of an individual chart.
Reading the contrast fairly
Popular writing often casts Jupiter as good and Saturn as bad. The classical view is more balanced. Jupiter's expansion can become excess, and Saturn's limitation can become the patience that makes lasting work possible. Saturn is also the graha of service and of the ordinary working person, and a well placed Saturn is read as giving endurance and fair judgement. A reader should look at the houses each rules for the given Lagna, their dignity and their aspects, rather than assigning blessings to one and troubles to the other by default.