Accompanied by the Illuminator of Hidden Meanings

By the measure of years: "by two, three, four, and the oceans" original: "dvicisugāgaraiḥ"; a mnemonic where 'oceans' represents the number 4. Following the rule that "numbers move from right to left," this results in four hundred and thirty-two. When multiplied by "ten thousand" ayutena, the total is known to be four million, three hundred and twenty thousand 4,320,000 years, the length of a Mahāyuga or Great Age.

Now, regarding the specific durations of the quarters within a Great Age: since no specific different measures are initially heard, one might assume they are equal based on the logic that "what is not specified should be equal." However, the text denies that each is simply a fourth part of the Great Age.

Of the Kṛta and the others: This refers to the Kṛta, Tretā, Dvāpara, and Kali ages.
By the arrangement of the pillars of Dharma: Dharmapāda-vyavasthayā The "feet" or pillars of righteousness/morality. The following arrangement or status should be understood, rather than an equal duration of time. The meaning is this: In the Kṛta Age, Dharma has four pillars; therefore, its duration is the greatest. Then, in the Tretā Age, because Dharma possesses only three pillars, the duration of the Tretā is shorter in proportion. Similarly, because Dharma possesses two pillars and one pillar in the Dvāpara and Kali ages respectively, their durations are proportionately shorter than the Kṛta and Tretā. Their measures are not equal. || 16 ||

Now, if a Great Age consists of ten parts in total (the sum of all the pillars of Dharma), then what is the specific measure of each? By using the rule of proportion with the previously mentioned figures, the author explains the specific knowledge of the measures of the Kṛta and other ages:

The "tenth part of the Age" refers to one-tenth of the previously mentioned 4,320,000 divine years. This part is multiplied fourfold, and then by four, three, two, and one in sequence. The result is the measure of the Kṛta, Tretā, Dvāpara, and Kali ages respectively.

One might ask: in the Law Books of Manu the Manusmṛti, the measures of the Kṛta and others are given in divine years as 4,000, 3,000... The text cuts off here, likely preparing to explain the addition of "sandhyā" or transitional periods.