People with a silent mind are very rarely found. This is the attribute only of those who use all means to attract to themselves Divine Grace and to be filled with the spiritual comfort flowing from it. Thus let us practice mental doing, this philosophy of Christ, in guarding our mind and in watchfulness…. Watchfulness is rightly called a Way, for it leads to the Kingdom – both the Kingdom within us and that of the Future. It is also called the workshop of the mind, for it fashions and polishes our mental character and transforms our soul from enslaved to free. Watchfulness is also like a small window through which God enters and appears to the mind.
St. Philotheus of Sinai,
Forty Texts on Watchfulness