Humani Generis §40

⁴⁰ Truly, we are aware that the majority of Catholic doctors, the fruit of whose studies is being gathered in universities, in seminaries and in the colleges of religious, are far removed from those errors which today, whether through a desire for novelty or through a certain immoderate zeal for the apostolate, are being spread either openly or covertly. But we know also that such new opinions can entice the incautious; and therefore we prefer to withstand the very beginnings rather than to administer the medicine after the disease has grown inveterate.