Forty degrees is a ninth of the circle, and the novile is the aspect that ninth defines. Like the other Keplerian additions it has no classical Western standing, since nine does not divide twelve and no pair of signs stands in a fixed novile relation to one another. It is measured in degrees or it is not found.
What distinguishes the novile from the septile and the quintile is that the number nine has independent weight in another living astrological tradition. In jyotisha the navamsha, the ninefold division of a sign into arcs of three degrees and twenty minutes, is among the most heavily used of all the divisional charts, second in importance only to the birth chart itself. The two techniques are not the same thing. The navamsha is a subdivision of a sign that generates a whole second chart; the novile is an angular relation between two planets. But they rest on the same division of the zodiac, and Western writers who defend the novile frequently point at the navamsha as evidence that a ninefold division of the circle is not an arbitrary invention.
That is an argument by analogy and it should be labelled as one. Jyotisha does not use a forty degree aspect, and its own aspect doctrine, the drishti, works on quite different principles. Western practice gives the novile a very narrow orb, often a single degree, and readings that turn on completion, gestation and things brought to term. As with the other minor aspects, the geometry is solid and the meaning is asserted.