[When]…we are living at peace, the truth will shine upon us and its radiance will illuminate the eyes of our soul.
Now this truth is God. Once in an ineffable and mysterious vision it manifested itself to Moses, and it is not without significance for us that the flame from which the soul of the Prophet was illuminated was kindled from a thorn-bush.
If truth is God and if it is also light – two of the sublime and sacred epithets by which the Gospel describes the God who manifested himself to us in the flesh – it follows that a virtuous life will lead us to a knowledge of that light which descended to the level of our human nature.
It is not from some luminary set among the stars that it sheds its radiance, which might then be thought to have a material origin, but from a bush on the earth, although it outshines the stars of heaven.
This also symbolizes the mystery of the Virgin, from whom came the divine light that shone upon the world without damaging the bush from which it emanated or allowing the virgin shoot to wither.
This light teaches us what we must do to stand in the rays of the true light, and that it is impossible with our feet in shackles to run toward the mountain where the light of truth appears.
We have first to free the feet of our soul from the covering of dead skins in which our nature was clad in the beginning when it disobeyed God’s will and was left naked.
To know that which is, we must purify our minds of assumptions regarding things which are not. In my opinion the definition of truth is an unerring comprehension of that which is.
He who is immutable, who does not increase or diminish, who is subject to no change for better or worse, but is perfectly self-sufficient; he who alone is desirable, in whom all else participates without causing in him any diminution, he indeed is that which truly is, and to comprehend him is to know the truth.
It is he whom Moses approached and whom today all approach who like Moses free themselves from their earthly coverings and look toward the light coming from the bramble bush, at the ray shining on us from the thorns, which stand for the flesh, for as the Gospel says, that ray is the real light and the truth.
Then such people will also be able to help others find salvation. They will be capable of destroying the forces of evil and of restoring those enslaved by them to liberty.
Gregory of Nyssa (c 335 – after 394): The Life of Moses, 2.17-26 (SC 1:36-39); from the Monastic Office of Vigils for Tuesday of the First Week in Lent, Year 2
Enlarging the Heart 