Ian Ker, in his biography, describes how Newman wrote to Birmingham after arriving in Rome, on his visit to receive the red hat:
On arriving in Rome a week or so later he wrote to Birmingham to ask one of the community to check if the words 'cor ad cor loquitur' ('heart speaks to heart') were to be found in the Vulgate version of the Bible or in Thomas a Kempis. He had forgotten that he had already quoted the saying from St Francis de Sales in the Idea of a University. It was, of course, to be the motto on his cardinal's coat of arms.This suggests that Newman's choice of motto was, if not completely "last minute", in all likelihood more intuitive than thought out.
In the years leading up to his being made a Cardinal by Pope Leo XIII, Newman had what might be described as a lively time. He was drawn into a number of controversies and projects, in which he engaged with all due vigour. His relations to ecclesiastical authority - Wiseman and Manning - weren't smooth, either on a personal level or a theological level, and generally caused him more anxiety than peace. The choice of motto seems rather unrelated to this rough and tumble experience of ecclesial life.
So, where was Newman coming from as he chose his motto, "heart speaks to heart"? If we assume that Newman was in some intuitive way reaching back to his previous encounter with this phrase, the context of his first citation of it in the Idea of a University might offer some insight into his choice.
Newman's citation of St Francis de Sales comes in a chapter of the Idea entitled "University Preaching", in which Newman considers what would make a good sermon preached in a university. Now, at the beginning of the second paragraph of this chapter, Newman writes:
So far is clear at once, that the preacher's object is the spiritual good of his hearers. "Finis praedicanti sit", says St Francis de Sales; "ut vitam (justitiae) habeant homines, et abundantius habeant".The purpose of preaching is, says St Francis de Sales, that men might have life, and have it in abundance. Newman goes on to insist that, more important than any of the natural skills that help to make a good preacher, is an intense awareness of this purpose:
Talent, logic, learning, words, manner, voice, action, all are required for the perfection of a preacher; but "one thing is necessary,"—an intense perception and appreciation of the end for which he preaches, and that is, to be the minister of some definite spiritual good to those who hear him.It is in the context of this earnestness for the spiritual good of his hearers that Newman places the longer quotation from St Francis de Sales that includes the phrase that, altered, will become the motto "heart speaks to heart" (my emphasis added):
It is this earnestness, in the supernatural order, which is the eloquence of saints ...St. Francis de Sales is full and clear upon this point. It is necessary, he says, "ut ipsemet penitus hauseris, ut persuasissimam tibi habeas, doctrinam quam aliis persuasam cupis. Artificium summum erit, nullum habere artificium. Inflammata sint verba, non clamoribus gesticulationibusve immodicis, sed interiore affectione. De corde plus quàm de ore proficiscantur. Quantumvis ore dixerimus, sanè cor cordi loquitur, lingua non nisi aures pulsat."
As a distinct image before the mind makes the preacher earnest, so it will give him something which it is worth while to communicate to others. Mere sympathy, it is true, is able, as I have said, to transfer an emotion or sentiment from mind to mind, but it is not able to fix it there. He must aim at imprinting on the heart what will never leave it, and this he cannot do unless he employ himself on some definite subject, which he has to handle and weigh, and then, as it were, to hand over from himself to others.