Yuga-Vibhāga and Kāla-Pramāṇa
Measures of Time and the Four Yugas
एष त्रेतायुगे धर्मस्त्रेतासंध्यां निबोधत / त्रेतायुगस्वभावानां संध्या पादेन वर्त्तते / संध्यापादः स्वभावस्तु सोंऽशपदेन तिष्ठति
eṣa tretāyuge dharmastretāsaṃdhyāṃ nibodhata / tretāyugasvabhāvānāṃ saṃdhyā pādena varttate / saṃdhyāpādaḥ svabhāvastu soṃ'śapadena tiṣṭhati
This is the dharma of the Tretā Yuga; understand also the Tretā-saṃdhyā, its twilight transition. The transition of Tretā’s nature proceeds with one ‘foot’; and that twilight-foot endures as a partial share (aṃśa).