The interpretation timeline

The First Vatican Council

Defined that the pope teaches infallibly when he speaks ex cathedra, and that God can be known with certainty by reason.

1869–1870 Rome, the Vatican
Summoned by
Pope Pius IX
Sat
8 December 1869 to 18 July 1870, when it was adjourned
Present
803 in all — 6 archbishop-princes, 49 cardinals, 11 patriarchs, 680 archbishops and bishops, 28 abbots, 29 generals of orders
What it defined
canons on the Faith and the constitution of the Church, and the infallibility of the pope when speaking ex cathedra

These facts as given by the Catholic Encyclopedia (1913), "Councils" PD

Post-Reformation

c. 1650 – 1900
1870
Event
The First Vatican Council

The First Vatican Council, under Pope Pius IX, defined the universal primacy of jurisdiction of the bishop of Rome over the whole Church, and his infallibility when, speaking ex cathedra, he defines a doctrine of faith or morals to be held by the whole Church.

1870
A.D.
“The same holy Mother Church holds and teaches that God, the beginning and end of all things, may be certainly known by the natural light of human reason, by means of created things; 'for the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made,' but that it pleased his wisdom and bounty to reveal himself, and the eternal decrees of his will, to mankind by another and a supernatural way : as the Apostle says, ' God, having spoken on divers occasions, and many ways, in times past, to the Fathers by the Prophets; last of all, in these days, hath spoken to us by his Son.' It is to be ascribed to this divine revelation, that such truths among things divine as of themselves are not beyond human reason, can, even in the present condition of mankind, be known by every one with facility, with firm assurance, and with no admixture of error.”
Source
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.