258
Śrimad-Bhāgavatam
[Canto 7, Ch. 15]
dravya-sūkṣma-vipākaḥ —the paraphernalia offered as oblations in the fire, such as food grains mixed with ghee;  ca —and;  dhūmaḥ —turned to smoke, or the demigod in charge of smoke;  rātriḥ —the demigod in charge of night;  apakṣayaḥ —in the dark fortnight of the moon;  ayanam —the demigod in charge of the passing of the sun;  dakṣiṇam —in the southern zone;  somaḥ —the moon;  darśaḥ —returning;  oṣadhi —plant life (on the surface of the earth);  vīrudhaḥ —vegetation in general (the birth of lamentation);  annam —food grains;  retaḥ —semen;  iti —in this way;  kṣma-īśa —O King Yudhiṣṭhira, lord of the earth;  pitṛ-yānam —the way of taking birth from the father's semen;  punaḥ-bhavaḥ —again and again;  eka-ekaśyena —one after another;  anupūrvam —successively, according to the gradation;  bhūtvā —taking birth;  bhūtvā —again taking birth;  iha —in this material world;  jāyate —one exists in the materialistic way of life.
TRANSLATION
My dear King Yudhiṣṭhira, when oblations of ghee and food grains like barley and sesame are offered in sacrifice, they turn into celestial smoke, which carries one to successively higher planetary systems like the kingdoms of Dhumā, Rātri, Kṛṣṇapakṣa, Dakṣiṇam and ultimately the moon. Then, however, the performers of sacrifice descend again to earth to become herbs, creepers, vegetables and food grains. These are eaten by different living entities and turned to semen, which is injected into female bodies. Thus one takes birth again and again.
PURPORT
This is explained in  Bhagavad-gītā  (9.21):
te taṁ bhuktvā svarga-lokaṁ viśālaṁ kṣīṇe puṇye martya-lokaṁ viśanti evaṁ trayī-dharmam anuprapannā gatāgataṁ kāma-kāmā labhante
“When those who follow the  pravṛtti-mārga  have enjoyed heavenly sense pleasure, they return to this mortal planet again. Thus, through the Vedic principles, they achieve only flickering happiness.” Following