I bow reverently before the perfect and absolute Buddha, the Welcome, Suchness, Supreme Purity, True Self, Great Bliss, Permanence, and proceed to explain in full the classification of the two cycles of the four ages.
The four great ages have as their referent the qualities of a cosmic cycle, while the four minor ages have as their referent the quality of the doctrine.
There are 4,320,000 human years in the cosmic cycle, a fourth of which constitutes a foot. One foot, two, three, and four, in sequence, constitute the ages of iron (432,000 years), bronze (864,000 years), silver (1,296,.000 years), and gold (1,728,000 years).
The four minor ages of the quality of the doctrine last for 21,600 human years, one foot of which is equivalent to 2,160 years.
The Dharma of the Golden Age is perfect, with all intact qualities.
As it declines by three fourths, the doctrine of the Bronze Age appears.
When not even a fourth part remains of the perfect Dharma, the doctrine of the Iron Age appears, the corrupt teaching of the ignorant.
Knowing well these four divisions, I long to purify the Dharma, and wishing for others and myself that we embark on the excellent path, I honor the Dharma of the Golden Age with my testimony.
—Dolpopa Sherab Gyaltsen, The Fourth Council
 2,160 human years (one foot), from the birth of Shakyamuni Buddha.
 2,160 years, from the end of the Golden Age of the Dharma.
 2,160 years, from the end of the initial Silver Age. The Silver Age has a duration of 4,320 years, or two feet of 2,160 tears each.
 6,480 years (three feet of 2,160 years), from the end of the posterior Silver Age.
 8,640 years (four feet of 2,160 years), from the end of the Bronze Age.