Factors that increase a planet’s strength are called dignities; those that weaken it, debilities. These are termed ‘essential’ when they rely upon zodiacal position; and ‘accidental’ if they rely upon anything else. Thus the advantage offered to a planet by being in its own sign or exaltation is an essential dignity, the disadvantage of being in its sign of detriment or fall is an essential debility; but combustion, aspectual connections and matters of angularity or house position are accidental dignities or debilities.