“Any person whatsoever can be concentrated, even for hours, thinking of a certain problem or a certain matter— without his attention being distracted by anything else.
     In earlier times also, when adding machines did not exist, accountants worked for eight hours doing additions without lifting their heads and without their mind wandering, even if a compressor was working next to them! Something analogous occurs with many students when they are occupied by their lessons. If, however, someone sets out to pray, then all the personal, family or business occupations project themselves before him and distract him. This is proof that the devil exists and (hat prayer burns him up. For this reason, he fights it.”
Elder St Ephiphanios of Trizina
– ‘Counsels for Life’