"Whosoever is speaking concerning God," says Gregory, "must be careful to search out thoroughly whatsoever furnishes moral instruction to his hearers; and should account that to be the right method of ordering his discourse which permits him when opportunity for edification requires it, to turn aside for a useful purpose from that which he had begun to speak of. He that treats of sacred writ should follow the way of a river: for if a river as it flows along its channel meets with open valleys on its side, into these it immediately turns the course of its current, and when they are copiously supplied presently it pours itself back into its bed. Thus unquestionably should it be with every one that treats the Divine word, so that if discussing any subject he chances to find at hand any occasion of seasonable edification he should as it were force the streams of discourse towards the adjacent valley, and when he has poured forth enough upon its level of instruction fall back into the channel of discourse which he had proposed to himself." We do not know what the reader may think of Gregory's geography; but certainly he carries out his discursive views to the full, and fills every valley he may chance to come to in his flowing, with pools and streams--no doubt waters of refreshing to the souls that surrounded him, ever eager to press him on. A commentary thus called forth by the necessities of the moment, spoken in the first place to anxious listeners who had with much pressure demanded it, and who nodded their heads over it with mingled approbation and criticism as half their own, has a distinctive character peculiar to itself, and requires little aid from science or learning. A large portion of it was written as it fell from his lips, without revision Gregory informs us, "because the brethren drawing me away to other things, would not leave time to correct this with any great degree of exactness."