The decile inscribes in the zodiacal circle the figure of the decagon, whose sides have an angular amplitude of 36°. The aspect belongs to the family of the quintile (72°), of which it is a submultiple (72/2); the extensions of the quintile are the bi-quintile (144°) and the tri-quintile (216°) to which, always considering the series derived from the fifth harmonic, the quindecile (24°, 360/15) and the vigintile ( 18°, 360/20) are added. As with the decile, they are a subset of the quintile, originating from dividing it by 3 and 4, respectively.
As with all minor aspects, but particularly those representing higher harmonic frequencies, the spectrum of manifestation becomes increasingly subtle; for a result to be detectable, the personality of reference must develop a particular harmony with the aspect, or rather that it has strengthened its more subtle sides. Alongside this consideration, it will be helpful to note that the tolerance accepted in the orbit of the aspect should not exceed the degree, given its approximation to the values of the novile (40°) and the undecile (about 33°).
Traditionally, the decile aspect is given a similar meaning to the quintile but slightly weakened; we could say that it expresses a minor talent or a creative tendency that is only partially developed. Numerological symbolism is not of great help in supporting this meaning: the number 10, in fact, represents the earthly and immanent manifestation of Unity: the human personality, which becomes the bearer of the instances of an ego limited by the bodily horizon . Going back to what was said for the novile, we can deconstruct the number 10 into 9 + 1, the expression of all gross and subtle level phenomena that find their point of cohesion in the individual conscience; still, as 5 + 5, the union of the pentagram with one point facing upward – the emancipated man – and the inverted pentagram – the pure personal impulse separated from its spiritual nature. Perhaps, in the latter case, the presence of opposing creative tensions – both higher and lower order or guided by the ego – can justify the meaning given to the decile of “lesser talent”, but in all honesty, the association seems quite dubious to us.
In the study of Harmonics, it should be emphasised that the tenth harmonic is not among the most used in practice. In Jyotisha (Indian) astrology, there is a method of subdividing the astrological chart which has similarities to the theory of Harmonics; with this method, called Varga (division), each zodiac sign is further divided following the numerical sequence. An additional horoscope is created by applying a series of rules, similar to what was done with the Harmonics technique. Well, the study of the Varga corresponding to the division by 10 (Dasamsa) allows us to shed light on individual karma and, by extension, on the potential for social and professional fulfilment brought to maturity thanks to inner evolution. It is the exact meaning expressed by the tenth Arcanum of the Tarot, the Wheel of Fortune; it also applies to the number 10, understood as an individual destiny on the microcosmic level.
The minor aspects, as proposed by part of the astrological community, sometimes present interpretative problems when compared with the pure numerical symbolism of reference, especially when considering the numerical series beyond 9. The best way to study them is probably a map highlighting a specific harmonic to isolate its significance or possible dominance over other harmonics.
 The zero represents unlimited unmanifested potential, the Ain Soph of the Kabbalists. Ain Soph gives rise to the first definition (the Unity or number 1, Kether in the Tree of Sephiroth) by concentrating a centre. The number 10, therefore, is nothing but a repetition of Unity on the contingent level, which in the Tree is Malkuth, the tenth Sephira, the immanent presence of God in creation. It is the exact meaning expressed in the image of the sun glyph, a circle with a dot in the centre. In the natal horoscope, the Sun symbolises the permanent principle (Logos) at the origin of the individual’s vital impulse.