6 Many things may be brought forward for the confutation of that madness. Meanwhile, however, if at any time they assail your ears, read this letter to the supporters of such error, and do not count it too great a labour to write back to me as well as you can what they say in reply. Let me add that our hearts are purified by faith, because the vision of God is promised to us as the reward of faith. Now, if this vision of God were to be through the bodily eyes, in vain are the souls of saints exercised for receiving it; nay, rather, a soul which cherishes such sentiments is not exercised in itself, but is wholly in the flesh. For where will it dwell more resolutely and fixedly than in that by means of which it expects that it shall see God? How great an evil this would be I rather leave to your own intelligence to observe, than labour to prove by a long argument.
May your heart dwell always under the Lord's keeping, noble and justly distinguished lady, and daughter worthy of honour in the love of Christ! Salute from me, with the respect due to your worth, your sons, who are along with yourself honourable, and to me dearly beloved in the Lord.
Source: Letters (New Advent)