If we are to pray with the necessary fervor and purity, the following discipline must be carefully observed.  First, you must completely surpass all the anxieties of the flesh…renounce all unkind and empty talk, gossip and clowning.  Above all, you must entirely expel the emotions of anger and sadness; you must uproot the noxious seedings of sensual desire and the spirit of possessiveness.  All such vices, that are visible even to our fellow men, must be cut away and destroyed.  But after this preliminary work of purification has received its crown of innocent simplicity and purity, the foundations must be laid; unshakable foundations of a deep humility, capable of bearing the tower that is to rise even to the heavens… –St John Cassian ‘Conferences’ quoted in ‘The Wound of Love’ by A. Carthusian.