Cultivation techniques were divided into Heaven, Earth, Profound, and Yellow. Yellow-tier Cultivation Techniques could only allow one to cultivate to Spirit Stream Tier Three, Profound-tier ones to Tier Six, and Earth-tier ones to Tier Nine.
The Spirit Stream Realm had only nine tiers. Logically speaking, an Earth-tier Cultivation Technique should have been enough for a Spirit Stream Realm cultivator to reach great completion.
In reality, that was not the case. Earth-tier Cultivation Techniques could only allow cultivators to open 180 Apertures, while the human body possessed a full 360 Apertures.
After cultivating to 180 Apertures, one had to switch to a Heaven-Grade Cultivation Technique in order to open more Spiritual Apertures.
A Spirit Stream Tier Nine cultivator who practiced an Earth-tier Cultivation Technique and had opened 180 Apertures could open the 181st Aperture after switching to a Heaven-Grade Cultivation Technique. However, switching cultivation techniques would cause their original realm to drop by several tiers. Under the Heaven-Grade Cultivation Technique's classification, 180 Apertures were only equivalent to Spirit Stream Realm Sixth Layer.
In short, the number of Spiritual Apertures a cultivator had opened was not the standard for judging their cultivation tier. What mattered was how many Minor Heavenly Circulations they possessed within their body.
Cultivators who had opened the same number of Spiritual Apertures did not necessarily have the same cultivation.
During the only Teaching Session he had attended, the Sect Master had explained the differences between cultivation techniques to Lu Ye, so he remembered these things.
Luo Ji appeared to be only a Spirit Stream Second Layer cultivator, but in truth, he had opened at least fifty Spiritual Apertures! The fluctuations of Spiritual Power when he cast spells were far stronger than Lu Ye's.
With a Heaven-Grade Cultivation Technique, opening 18 Apertures counted as Tier One, while 45 Apertures