250
Śrimad-Bhāgavatam
[Canto 5, Ch. 19]
mode of goodness;  lohita —of the mode of passion;  kṛṣṇa —of the mode of ignorance;  varṇena —according to the division;  sva —by himself;  ārabdhena —begun;  karmaṇā —by activities;  divya —divine;  mānuṣa —human;  nāraka —hellish;  gatayaḥ —goals;  bahvyaḥ —many;  ātmanaḥ —of his own;  ānupūrvyeṇa —according to acts performed previously;  sarvāḥ —all;  hi —certainly;  eva —indeed;  sarveṣām —of all of them;  vidhīyante —are allotted;  yathā-varṇa-vidhānam —in terms of different castes;  apavargaḥ —the path of liberation;  ca —and;  api —also;  bhavati —is possible.
TRANSLATION
The people who take birth in this tract of land are divided according to the qualities of material nature—the modes of goodness [sattva-guṇa], passion [rajo-guṇa], and ignorance [tamo-guṇa]. Some of them are born as exalted personalities, some are ordinary human beings, and some are extremely abominable, for in Bhārata-varṣa one takes birth exactly according to one's past karma. If one's position is ascertained by a bona fide spiritual master and one is properly trained to engage in the service of Lord Viṣṇu according to the four social divisions [brāhmaṇa, kṣatriya, vaiśya and śūdra] and the four spiritual divisions [brahmacāri, gṛhastha, vānaprastha and sannyāsa], one's life becomes perfect.
PURPORT
For further information, one should refer to  Bhagavad-gītā  (14.18 and 18.42-45). Śrīla Rāmānujācārya writes in his book  Vedānta-saṅgraha :
evaṁ-vidha-parābhakti-svarūpa-jñāna-viśeṣasyotpādakaḥ pūrvoktāharahar upacīyamāna-jñāna-pūrvaka-karmānugṛhīta-bhakti-yoga eva; yathoktaṁ bhagavatā parāśareṇa—varṇāśrameti. nikhila-jagaduddhāraṇāyāvanitale 'vatīrṇaṁ para-brahma-bhūtaḥ puruṣottamaḥ svayam etad uktavān—  “svakarma-nirataḥ siddhiṁ yathā vindati tac chṛṇu” “yataḥ pravṛttir bhūtānāṁ yena sarvam idaṁ tatam/ svakarmaṇā tam abhyarcya siddhiṁ vindati mānavaḥ”
Quoting from the  Viṣṇu Purāṇa  (389), the great sage Parāśara Muni has recommended: