For traditional sources, how does the Catholic Church distinguish between holy truth and human speculation from the same author?

Question

Some denominations believe that the Bible is the sole source of revealed knowledge (e.g. Protestant Sola scriptura).

Some believe that recorded oral tradition that doesn't contradict the Bible is a complementary source of truth (e.g. Judaism and the Talmud).

Others believe that tradition, even if it overrides the Bible, is an additional source (e.g. Catholicism and Tradition and Living Magisterium).

Among the traditions used by this third group, are individual authors whose writings contain both knowledge that is used as the basis of doctrine, and knowledge that is rejected as being against doctrine.

For instance Origen is a much-referenced source of tradition, but in Levit., Hom. VIII, in Migne P.G., XII, 495 he wrote:

… of all the holy people in the Scriptures, no one is recorded to have kept a feast or held a great banquet on his birthday. It is only sinners (like Pharaoh and Herod) who make great rejoicings over the day on which they were born into this world below …

Here Origen implies that the celebration of birthdays is a pagan practice, and that celebrating one's own birth day, or a saint's or Jesus's birth day, would be a sin. The Catholic Church however has clearly chosen to reject it as holy truth.

The question is, what methods are used to decide that one particular fact is divine truth while another one by the same author is merely human speculation?

Clarification:

This question was inspired by the given Origen quotation, but it looks like Origen was a poor choice for an example. He is more famous for posing "interesting" or awkward questions than for original ideas that became doctrine.

If someone can suggest a better example, please do.

And it stands to reason that there must be more suitable examples:

• At least some Catholic doctrine originates from extra-biblical tradition (otherwise it would be sola scriptura).
• At least some of that person's writing must be considered non-doctrinal and possibly untrue or speculative (otherwise it would be equivalent to scripture).

So even without a real example, the question itself still stands.

Answer 1

Inspiration applies to Scripture, not to anything else. According to the Catholic Encyclopedia:

inspiration is nothing else but the biblical text itself. This text was destined by God, Who inspired it, for the universal Church, in order that it might be authentically recognized as His written word. This destination is essential. Without it a book, even if it had been inspired by God, could not become canonical; it would have no more value than a private revelation. That is why any writing dated from a later period than the Apostolical age is condemned ipso facto to be excluded from the canon.

Thus the only books considered to be inspired by the Catholic Church are the books of the Bible, "as they left the pen of the sacred writers"^ibid

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Tradition (insofar as it is distinct from Scripture) does not "override the bible" for Tradition and Scripture together form the unified Deposit of Faith.