Nicene and Post-Nicene Fathers, Vol. III:
Doctrinal Treatises of St. Augustin: Section 18

18. But in truth was there either decree of any law, or power of gainsayers, or vile character of persons consecrated, or shameful report, or newness of institution, or hidden profession, to recall us from, and forbid us, the search? There is nothing of these. All laws divine and human allow us to seek the Catholic Faith; but to hold and exercise it is allowed us at any rate by human law, even if so long as we are in error there be a doubt concerning divine law; no enemy alarms our weakness, (although truth and the salvation of the soul, in case being diligently sought it be not found where it may with most safety, ought to be sought at any risk); the degrees of all ranks and powers most devotedly minister to this divine worship; the name of religion is most honorable and most famous. What, I pray, hinders to search out and discuss with pious and careful enquiry, whether there be here that which it must needs be few know and guard in entire purity, although the goodwill and affection of all nations conspire in its favor?