*The Moon in the 5th house.
Brihat Parasara Hora Sastra
*The first house indicates the intellect, intelligence and the brain.
*Moon, Jupiter and Venus in the 10th house—beautiful; very brave; endowed with sons and friends; has abundant wealth earned by his vast intelligence.
*Birth in Ashwini nakshatra—the native has a great deal of intelligence.
*Moon in Pushya—possesses wealth and intelligence.
*If Jupiter is in exaltation, his own sign, or the 9th house, then the native becomes a lord of great beneficence equal in status to kings and admired for his conspicuous intelligence, energy and other great qualities.
*The fifth house is the house of intelligence.
*Jupiter equals intelligence.
*When Jupiter aspects Mercury in Sagittarius or Pisces, the native will be rich by memory, intelligence and ancestors; furthermore, he is beautiful, noble and knowledgeable; he will be a king's minister or his treasurer; he is also a writer.
*Moon in the 9th house equals intelligence.
*Mercury in the 10th house indicates distinguished intelligence.
*If all the natural benefics are in benefic rashis in houses 2, 5, 8, and 11 while the natural malefics occupy dual signs, the native becomes a king, destroys all his enemies and is equal to Jupiter in intelligence.
*In a favorable Moon dasha, the native achieves success in undertakings out of his intelligence.
*Favorable Mercury dasha equals high intelligence.
*If the ascending degree is in the first half of Cancer, the native has eminence and intelligence.
*Intelligence is indicated by the 5th house, Mercury and the lord of the 5th house.
*If Mercury has full strength, and the 5th lord is aspected by a benefic and the 5th house is occupied by a benefic, the native possesses a keen intellect.
*If the lord of the navamsha occupied by the 5th lord is in a Kendra or trine and is aspected by the 5th lord, the native possesses keen intelligence.
*If the 5th lord is a benefic and is conjunct a benefic or in the sign of a benefic, then the native becomes a man of intelligence and wise.