I am not asking about Guna based system. Here 1 and 2 rising in varna hierarchy is mentioned but it says a Sudra will be born as a Vasihya then a Ksatriya and then a Bramhana. Cant a Sudra's next birth be Bramhana?
The same linked url gives the answer:
By these good acts, again, O goddess, when performed, a Sudra becomes a Brahmana, and a Vaisya becomes a Kshatriya.
It is with the aid of these acts, O goddess, that a person who has sprung from a degraded order, viz., a Sudra, may become a Brahmana refined of all stains and possessed of Vedic lore.
I have thus told thee a mystery, viz., the manner in which a Sudra may become a Brahmana
Manu 9.335 - If he is pure, attendant upon his superiors, of gentle speech, free from pride, and always dependent upon the Brāhmaṇa,—he attains a higher caste.
He attains a ‘higher caste’—such as the Brāhmaṇa and the rest.
Normally people acquire the next higher caste, but if they are really spiritual, then they can be a brahmana next birth.
If you die a Shudra I think Manusmriti (Chapter 9) gives a way in which you can:
शुचिरुत्कृष्टशुश्रूषुर्मृदुवागनहङ्कृतः । ब्राह्मणाद्याश्रयो नित्यमुत्कृष्टां जातिमश्नुते ॥ ३३५ ॥
If he is pure, attendant upon his superiors, of gentle speech, free from pride, and always dependent upon the Brāhmaṇa,—he attains a higher caste.—(335)
Now the words "next life" are not given here. But considering that no other verse in Manusmriti supports Varna change in this birth explicitly, and probably at least more than a hundred verses support caste / varna by birth only - we can assume this also means in the next life. This is also assumption of some translators. For example this translation:
- (A Sudra who is) pure, the servant of his betters, gentle in his speech, and free from pride, and always seeks a refuge with Brahmanas, attains (in his next life) a higher caste.
The above is translated by G. Buhler and you can find same thing in hindi translations also. Like this one by pandit GP Dwivedi
.....वह क्रम से उत्तम जाती में जन्म पता है ।
So the word born is used. Although this could also refer to second birth. But there is no indication in Manusmriti that this is possible. Shudra is considered unfit for sacraments. So it has to be next birth. After all, smriti supports birth system !!