There are essentially three things to consider when interpreting any planet in a horoscope: (1) How positive / negative is it? (2) How much power and umph is behind that positivity or negativity? (3) How does the planet get, or not get, the opportunity to deliver that positive / negative umph.
The first question is answered by the theory of dignity; the second by the theory of potency; the third by the theory of alignment.
Dignity is a way to evaluate how well a planet gets along with the planet that “hosts” it. Every planet owns a sign, that planet is the “host” of any planet that happens to be in its sign. The measure of sweet/sour in the relationship between the host and guest is called “dignity.” The sweeter the relationship, the more positive the guest behaves in the horoscope, and visa versa.
“Bala” is a way to evaluate how much umph a planet has. There are more than a dozen factors that work together to determine this.
“Alignment” is a question of how accurately a planet lines up with the degree of the more important points in the horoscope: Ascendant, Moon, and Sun.
Taking these three factors into consideration, an astrologer can make relatively sophisticate judgements and interpretations.
– Vic DiCara