The Fragrance-Tracking Technique was a very basic spell, primarily used in conjunction with a Tracking Talisman.
Because it was so basic, many Spirit Children who had joined a Daoist School without entering the Daoist Order could use it with ease.
Incidentally, the Daoist Schools in the mundane world were very fond of checking prospective disciples' birth dates and times to see whether they had a destined affinity. That "affinity" meant determining whether the disciple was a Spirit Child.
Zhang Xiao changed his hand seal and pointed two fingers at the three sticks of incense. They burned away at astonishing speed, yet their ashes remained perfectly still in the biting wind.
He tapped the ground with his toes three times, producing three soft sounds, then pressed his palms together and thrust them forward. Dust suddenly swirled inside the circle he had drawn with his foot on the bare earth.
The pale gray incense ashes toppled in response, as though someone invisible were using them as a brush to draw a thin, winding line inside the circle.
Zhang Xiao turned his hand over and took out the Compass. He did not know how to use its more complicated functions, but reading a direction with the help of the Tracking Technique was no problem.
What respectable Daoist couldn't use a compass properly, right, Zhang Xiao?
On the Compass, zi, wu, mao, and you represented the four cardinal directions. Together with eight other characters, they formed the Twelve Mountains.
In other words, it was divided into twelve bearings. Later generations added another twelve, creating the Twenty-Four Mountains.
Each bearing of the Twenty-Four Mountains covered fifteen degrees, with three totaling forty-five degrees. Each set of three belonged to one of the eight directions, represented by a Bagua trigram.
Zhang Xiao stared at the incense ashes,