The elemental categories are called triplicities because each classical element is associated with three signs[21][22] The four astrological elements are also considered as a direct equivalent to Hippocrates' personality types (sanguine = air; choleric = fire; melancholic = earth; phlegmatic = water). A modern approach looks at elements as "the energy substance of experience"[32] and the next table tries to summarize their description through keywords.[33][34] The elements have grown in importance and some astrologers begin natal chart interpretations by studying the balance of elements in the location of planets (especially the Sun's and Moon's ascendant signs) and the position of angles in the chart.[35] Polarity Element Symbol[36] Keywords Sign triplicity Positive Fire Assertion, drive, willpower Aries, Leo, Sagittarius Air Communication, socialization, conceptualization Gemini, Libra, Aquarius Negative Earth Practicality, caution, material world Taurus, Virgo, Capricorn Water Emotion, empathy, sensitivity Cancer, Scorpio, Pisces