The Greeks had a word for it, of course. Many words, actually. Orthodox writer Scott Cairns discusses several of these in an interesting on-line essay dealing mainly with nous and kardia and how they have been translated somewhat simplistically into English as "mind" and "heart". Cairns sees the primary mission of the church as healing the spiritual sickness of its members. And the way to do this is to inculcate a way of prayer that draws the "mind" into the "heart".

I preface the Cairns excerpt with a brief definition of nous by Greek theologian John Romanides.

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Romanides

...nous [is] this noetic energy that functions in the heart of every spiritually healthy person...It functions in the brain as the reason; it simultaneously functions in the heart as the nous. In other words, the same organ, the nous, prays ceaselessly in the heart and simultaneously thinks about mathematical problems, for example, or anything else in the brain.

Cairns

Virtually every time we come across the word mind (or, in some cases, intellect or reason) in an English translation of the New Testament, nous is the word being rendered. One might say that it is the word being surrendered.

The greatest danger is that what should be an actively performed faith, a lived faith, becomes little more than an idea. When it is most healthy, ours is not simply a propositional faith, but a faith embodied and performed. Having lost this understanding, much of Western Christendom and much of an unduly influenced Eastern Church, has squandered the single most essential aspect of the Christian life: that we are ill, that what we need most is to be healed--our nous purified, illuminated, and restored to the actual communion with the God who is.

...Another New testament word that could benefit from a rigorous appraisal is kardia, offered to us simply as heart. Early Christians understood kardia as the very center of the complex human person, and as the scene of our potential repair...

The more we read in the fathers and mothers across the early centuries of the Church, the more profoundly we come to recognize this formula, this admonition that we might find our prayer lives made fruitful by our descending with our "minds" into our "hearts". This figure, then--of the lucid nous descended into the ready kardia, of the mind pressed into the heart--articulates both the mode and locus of our potential re-collection, our much desired healing. At the very least, it identifies the scene where this reconstitution of our wholeness might begin: the center of the human body, which is nonetheless the temple of the Holy Spirit.