The biquintile is an aspect of one hundred and forty-four degrees, formed by taking two-fifths of the circle, twice the seventy-two-degree quintile. Both are minor aspects derived from dividing the circle by five, a division not among the classical Ptolemaic set but introduced by Kepler, who valued the fivefold aspects highly. Given a narrow orb, the biquintile is read in the tradition as a relation of talent, creativity, and a distinctive, self-directed skill, the fifth-harmonic quality of style, artistry, and the shaping power of the will, sharing the character of the quintile in a doubled form. These are the interpretive conventions of the astrological tradition for this angular relation, one of the subtler aspects that supplement the major figures with the creative fivefold shadings Kepler added to the astrologer's vocabulary of angles.
The biquintile, twice the quintile's thirty-six-degree unit at one hundred and forty-four degrees, belongs to the fifth-harmonic family that Kepler introduced in his Harmonices Mundi of 1619, where he connected the geometry of the regular pentagon to musical consonance and to what he took to be a corresponding astrological effect. Kepler regarded the quintile and its multiples as aspects of a different order from the traditional five, tied to individual creative or technical talent rather than to the broader temperamental and circumstantial matters the Ptolemaic aspects govern, and that reading has persisted in the harmonic astrology that developed from his work in the twentieth century, particularly in the writing of John Addey. The orb given to it is narrow, and it remains one of the aspects used chiefly by astrologers working explicitly within the harmonic tradition rather than in general practice.