As well might the eye ascertain an object put before it while it is wandering restless up and down and sideways, without fixing a steady gaze upon it, as a mind, distracted by a thousand worldly cares, be able clearly to apprehend the truth.
[...] Each day, as it comes, darkens the soul in its own way; and night after night takes up the day’s anxieties, and cheats the mind with illusions in accordance.
Now one way of escaping all this is separation from the whole world; that is, not bodily separation, but the severance of the soul’s sympathy with the body, and to live so without city, home, goods, society, possessions, means of life, business, engagements, human learning, that the heart may readily receive every impress of divine doctrine.
Preparation of heart is the unlearning the prejudices of evil converse. It is the smoothing the waxen tablet before attempting to write on it.
Now solitude is of the greatest use for this purpose, inasmuch as it stills our passions, and gives room for principle to cut them out of the soul.
[...] Let there then be such a place as ours, separate from intercourse with men, that the tenor of our exercises be not interrupted from without.
Pious exercises nourish the soul with divine thoughts. What state can be more blessed than to imitate on earth the choruses of angels? to begin the day with prayer, and honour our Maker with hymns and songs?
As the day brightens, to betake ourselves, with prayer attending on it throughout, to our labours, and to sweeten our work with hymns, as if with salt? Soothing hymns compose the mind to a cheerful and calm state.
Quiet, then, as I have said, is the first step in our sanctification; the tongue purified from the gossip of the world; the eyes unexcited by fair colour or comely shape; the ear not relaxing the tone or mind by voluptuous songs, nor by that especial mischief, the talk of light men and jesters.
Thus the mind, saved from dissipation from without, and not through the senses thrown upon the world, falls back upon itself, and thereby ascends to the contemplation of God.
Basil the Great (330-379): Letter 2,2 (trans. John Henry Newman).