John Cassian, Conferences I–X IX.26: Of the different causes of conviction

But who is able, with whatever experience he may be endowed, to give a sufficient account of the varieties and reasons and grounds of conviction, by which the mind is inflamed and set on fire and incited to pure and most fervent prayers? And of these we will now by way of specimen set forth a few, as far as we can by God’s enlightenment recollect them. For sometimes a verse of any one of the Psalms gives us an occasion of ardent prayer while we are singing. Sometimes the harmonious modulation of a brother’s voice stirs up the minds of dullards to intense supplication. We know also that the enunciation and the reverence of the chanter adds greatly to the fervour of those who stand by. Moreover the exhortation of a perfect man, and a spiritual conference has often raised the affections of those present to the richest prayer. We know too that by the death of a brother or some one dear to us, we are no less carried away to full conviction. The recollection also of our coldness and carelessness has sometimes aroused in us a healthful fervour of spirit. And in this way no one can doubt that numberless opportunities are not wanting, by which through God’s grace the coldness and sleepiness of our minds can be shaken off.