48 This true liberty of the children of God, which adheres faithfully to the teaching of the Church and accepts and uses gratefully the contributions of profane science, this liberty, upheld and sustained in every way by the confidence of all, is the condition and source of all lasting fruit and of all solid progress in Catholic doctrine, as Our Predecessor of happy memory Leo XIII rightly observes, when he says: "unless harmony of mind be maintained and principle safeguarded, no progress can be expected in this matter from the varied studies of many."
Source: Divino Afflante Spiritu (Vatican.va)