Seven rungs of strength
Dignity measures one thing: how strongly a planet can express its nature in a sign. The ladder, top to bottom: exaltation (uccha), moolatrikona, own sign (svakshetra), friend's sign, neutral, enemy's sign, debilitation (neecha). Every placement you will ever judge stands on one of these seven rungs.
Jupiter in Cancer speaks at full volume; Jupiter in Capricorn can barely whisper.
Exaltation — learn these cold
Each planet has one sign of exaltation, with a degree of deepest strength inside it: Sun 10 Aries, Moon 3 Taurus, Mars 28 Capricorn, Mercury 15 Virgo, Jupiter 5 Cancer, Venus 27 Pisces, Saturn 20 Libra. These seven facts are the only raw memorization this lesson asks of you.
Saturn — slow, harsh, judicial — is at his best in Libra, the sign of the balance.
Debilitation is free — derive it
Debilitation, the bottom rung, is always the exact opposite sign at the same degree. Sun exalted at 10 Aries means Sun debilitated at 10 Libra; Moon exalted at 3 Taurus means Moon debilitated at 3 Scorpio. Memorize seven facts, know fourteen. Never learn debilitations separately.
Venus: 27 Pisces exalted, so 27 Virgo debilitated. Count six signs across.
Moolatrikona — a planet's favorite seat at home
Moolatrikona is a planet's preferred stretch of one of its own signs — treated stronger than plain own sign, weaker than exaltation. The sign-level list: Sun in Leo, Moon in Taurus, Mars in Aries, Mercury in Virgo, Jupiter in Sagittarius, Venus in Libra, Saturn in Aquarius. Degrees exist, but they are reference detail.
The Moon's is Taurus — her exaltation sign — running 4 to 30 degrees, after the 3-degree exaltation point.
Mercury is exalted at home
Mercury alone is exalted in his own sign. Virgo holds three rungs at once, sliced by degree: 0 to 15 exaltation, 16 to 20 moolatrikona, the remainder plain own sign. When Mercury is in Virgo, you cannot name his dignity until you know his degree.
Mercury at 10 Virgo is exalted; at 25 Virgo, merely in his own sign.
Rahu and Ketu — the honest answer is 'texts differ'
BPHS gives the nodes no sign rulerships, and the classics split on their exaltation. The most common modern convention exalts Rahu in Taurus and Ketu in Scorpio — but that is convention, not consensus. When the tradition disagrees with itself, say so; inventing certainty is worse than admitting a split.
Ask three jyotishis about Rahu's exaltation and you may hear Taurus, Gemini, or a shrug.
The one idea to keep
Volume, never loyalty
Dignity answers 'how strong?', never 'whose side?'. Which planets work for or against a chart comes from lordship — a separate measurement you'll build in module 4. A debilitated friend is a weak friend; an exalted adversary is a strong adversary. Never confuse volume with loyalty.