Why? Why both the Holy Scripture and the Holy Tradition? Does it not seem plainly clear that one source - the Holy Scripture alone - is sufficient in matters of faith and morals? Why the need for Tradition? Is Tradition not merely, after all, man-made? Are the Holy Scriptures not the only word from God that has been bequeathed to us for our salvation?

Prima facie - on the face of it - this argument seems right.

But as history has pointed out unambiguously...

...theology that is not in service to "the faith once delivered to the saints" (Jude 3) will, in time, turn against the faith once delivered to the saints.

Ideas that are not held accountable to "the Church of the living God, the pillar and bulwark of truth" (1 Tim 3:15) will, in time, become the enemy of that truth.

For the same reason, the sola scriptura principle, as we know from sad experience, is "so protean and subject to variation that it results either in gutting the tradition or in creating new traditions around which further schisms are formed".

Hence the non-negotiable necessity for both Scripture and Tradition, both mirroring each other. Scripture constitutes the teachings of the Holy Apostles transmitted through documentation, and Tradition constitutes the teachings of the Holy Apostles transmitted orally; both preserved by the One Holy Catholic Apostolic Church of Jesus Christ.

[ A reflection of my reading from Richard John Neuhaus, Catholic Matters: Confusion, Controversy, and the Splendor of Truth, p.58. ]