@Sunstone So, now to answer your original query straight on:
Is it detectable at all?
The Catechism of the Catholic Church states that all divine grace, including this prevenient grace, "
surpasses the power of human intellect and will" so you might say that, in that sense, it isn't quite 'detectable' - if by this you mean something that can be measured quantitatively (like physical measurements) or even determined qualitatively based upon our feelings, thoughts and emotions (
qualia).
However, we know as believing Christians - based upon the bible and church doctrine - that all people possess this 'light of Christ', whether they actualise it or not.
Additionally, we have the lived experiential witness of the great mystics of the Church who have plumbed the depths of human spirituality and become
saints, living exemplars and mediators of God's grace. And many of them have written about this doctrine as it applies to the spiritual life - and they have given it many names, such that in this sense it is
detectable. We see the 'fruits' of it in acts of human goodness, perfect love, charity, altruism and in contemplation / meditative states of inner purity.
In this sense, St. Cyprian of Carthage (c. 200 – 258 AD) - another important early church father - explained the qualities to be expected from a life of habitual divine grace:
CHURCH FATHERS: Treatise 8 (Cyprian of Carthage)
"
This is truly to become sons of God by spiritual birth; this is to imitate by the heavenly law the equity of God the Father. For whatever is of God is common in our use; nor is any one excluded from His benefits and His gifts, so as to prevent the whole human race from enjoying equally the divine goodness and liberality. Thus the day equally enlightens, the sun gives radiance, the rain moistens, the wind blows, and the sleep is one to those that sleep, and the splendour of the stars and of the moon is common. In which example of equality, he who, as a possessor in the earth, shares his returns and his fruits with the brotherhood of his fellow man, while he is common and just in his gratuitous bounties, is an imitator of God the Father."
But in the more 'mystical' sense of the term....
From Abba
Evagrius (345-399 AD), the first hesychast, and the Desert Fathers who followed him, we learn about "
clear thinking" or "
clear sight" of the image of God within one's heart, untainted by the obscuration of the passions and
logismoi (disturbing thoughts)
- the kind of passionate, wild thoughts that distract our attention and scatter the focus of the mind away from God. The Desert Fathers called this '
apatheia' which means a state of imperturbable calm. If this state of mind was achieved, this
apatheia, the monks believed that they could see the undistorted light of their own mind, the image of God within them, which reflects the Divine Light:
"...The Kingdom of Heaven is apatheia [imperturbable calm, dispassion] of the soul along with true knowledge of existing things.
The proof of apatheia is had when the mind begins to see its own light, when it remains in a state of tranquillity in the presence of the images it has during sleep, and when it maintains its calm as it beholds the affairs of life.
The spirit that possesses health is the one which has no images of the things of the world at the time of prayer.
The ascetic life is the spiritual method for cleansing [the mind]..."
- Abba Evagrius Ponticus (345-399 AD), Early Desert Father
The true nature of the mind is described as "luminous" like sapphire when freed of incoming defilements (that is attachment to sense-impressions and mental images). Abbas Evagrius again:
"...If one wishes to see the state (katastasis) of the mind, let him deprive himself of all representations, and then he will see the mind appear similar to sapphire or to the color of the sky. But to do that without being passionless (apatheia) is impossible...The mind would not see itself unless it has been raised higher than all the representations of objects...
Apatheia (passionlessness) is a quiet state of the rational soul. It results from gentleness and self-control...
A man in chains cannot run. Nor can the mind that is enslaved to passion see the place of spiritual prayer. It is dragged along and tossed by these passion-filled thoughts and cannot stand firm and tranquil...
The ascetical mind is one that always receives passionlessly the representations of this world...The state of the mind is an intellectual peak, comparable in color to the sky. Onto it, there comes, at the time of prayer, the light of the holy Trinity..."
- Abba Evagrius Ponticus (345-399 AD), early desert father
In the medieval mystical tradition of the Catholic Church, this concept of the "
sapphire light of the dispassionate mind" was embellished further by our monks, friars and mystics into the idea that the mind was a dual phenomenon: with a lower seat rooted in the imagination and emotions, and the intellect; while above this (or below it, if you like) was the "
apex", "
ground" and "
essence" of the soul, wherein contemplative prayer takes place, and union with God.
As the Benedictine monk Dom Cuthbert Butler explained in his 1922 book,
Western Mysticism (p.140):
Western Mysticism
It is a common teaching of mystic writers that introversion is effected by a successive silencing of the faculties of the mind and of the powers of the soul, till the actuations become blind elevations to God; and in the 'Quiet' thus produced, the very being of the soul the "Ground of the Spirit', the later mystics call it comes into immediate relation with the Ultimate Reality which is God.
This at least will be held by all who regard the mind as something other than a bundle of sensations, phantasmata, emotions, cognitions, volitions. This essence of the soul, the soul itself, is what the mystics mean when they speak of the centre of the soul, or its apex, or ground, or the fund of the spirit, or the synteresis. 2 It has been called also in modern terminology the core of personality, and the transcendental self.
For the Catholic mystics it is this essence of the soul that enters into union with God. This we learned from Pope St Gregory the Great: he says that the mind must first clear itself of all sense perceptions and of all images of things bodily and spiritual, so that it may be able to find and consider itself as it is in itself, i.e., its essence; and then, by means of this realization of itself thus stript of all, it rises to the contemplation of God
At the end of his
Book of Spiritual Instruction Abbot Louis de Blois, O.S.B., (1506 – 1566), a Flemish monk and mystical writer, sets forth at some length the doctrine of the Catholic mystics on this hidden essence of the soul/mind:
Few rise above their natural powers; few ever come to know the
apex of the spirit and the hidden fund or depth of the soul. It is far
more inward and sublime than are the three higher faculties, for it
is their origin. It is wholly simple, essential, and uniform, and so
there is not multiplicity in it, but unity, and in it the three higher
faculties are one thing. Here is perfect tranquillity, deepest silence,
because never can any image enter here. By this depth, in which
the divine image lies hidden, we are deiform. This same depth is
called the heaven of the spirit, for the Kingdom of God is in it, as
the Lord said:
'The Kingdom of God is within you';
and the Kingdom of God is God Himself with all His riches. Therefore this naked
and unfigured depth is above all created things, and is raised above
all senses and faculties; it transcends place and time, abiding by a
certain perpetual adhesion in God its beginning; yet it is essentially
within us, because it is the abyss of the mind and its most inward
essence. This depth, which the uncreated light ever irradiates, when
it is laid open to a man and begins to shine on him, powerfully
affects and attracts him. . . .
A later monastic writer, Pere Noel, in summarizing the thought of the earlier German mystic and Catholic preacher
Johannes Tauler (c. 1300 – 15 June 1361), explains it thus:
"Do you wish to live truly of the divine life, to submit yourself fully to the illuminations of the Primary Truth, to experience the direct irradiations of the Divinity?
Leave matter and the senses, go forth from this visible world, quit creatures, pass over the matter that encloses you, the sensations that hold you in, the imaginations that keep you captive, the thoughts and sublime concepts which you take for the Primary Truth, but which are only a magnificent though fragile scaffolding of your reason. Raise yourself above your reason, above your human intelligence which nourishes itself on phantasms, images, sensible species; descend into the fund and the inmost recess of your soul: there you will find the pure and subsistent spirit; there you will find the dwelling-place of God; there you will find God."