अग्निनिचयः (Agninichaya) / The Accumulation of Sacred Fire & the Classification of Pitṛs by Time-Order
इत्येते पितरो ज्ञेया ऋतवश्चार्तवाश्च ये / सर्वभूतानि तेभ्यो यदृतुकालाद्विजज्ञिरे
ityete pitaro jñeyā ṛtavaścārtavāśca ye / sarvabhūtāni tebhyo yadṛtukālādvijajñire
Thus these Pitṛs are to be known as the Seasons and also as the Ārtavas; for from them all beings were born, according to the time of the seasons.