The First Part
Chapter 13
124 ON THE VARYING STATES WHICH COME TO THOSE WHO LIVE IN SOLITUDE, AS IS JUSTLY ORDERED BY GOD CONCERNING THIS [SPIRITUAL] WAY: NOW SADNESS AND PSYCHIC SUFFOCATION, THEN, SUDDENLY, GLADNESS AND JOY AND HOT FERVOUR AND UNUSUAL STRENGTH. PRAISE TO HIM THAT HAS ORDERED OUR WAY AMEN
To him who has determined to order his being in lonely dwelling and to pass the remainder of his days in service and in the ordering of the way of solitude, it will come to pass that, while he is as usual, in solitude, such as is justly prescribed by divine grace, his soul will be hidden in darkness. And just as the radiance of the sun is hidden from the earth by thick clouds, so, for a short time he is bereft from spiritual consolation and from the rays of grace, by the clouds of the affections; and some of the joy-giving force is withdrawn from him, while an unusual darkness falls upon his spirit; yet his mind is not troubled nor inclined towards dejection; but he remains patient, occupying himself with the writings of divine men and with prayers to which he forces himself, looking for help.
Then of a sudden it will be given him unexpectedly. For, as the face of the earth is gladdened by the rays of the sun when the dense atmosphere is torn asunder, so the words of prayer are able to tear away and to remove from the soul the 125 dark cloud of the affections and to gladden and to illuminate the spirit by the rays of joy and consolation which is born in our deliberations.
Especially when the soul is able to have recourse to the profit from the holy books and from vigils that make the mind pure. Constant meditation upon the holy scriptures will perpetually fill the soul with incomprehensible ecstasy and joy in God.
Source: Wensinck, A. J., trans. 1923. Mystic Treatises by Isaac of Nineveh. Amsterdam: Uitgave Der Koninklijke Akademie Van Wetenschappen. Page 84.