St Justin Popovich | ...impurity and heaviness of the intellect come from a satiated stomach.

According to St Isaac, impurity and heaviness of the intellect come from a satiated stomach. Fasting is therefore the chief means of purifying the intellect. The intellect is by nature fine and delicate, while heaviness is an unnatural addition introduced by sin. It is through prayer that the intellect isrefined and rendered clear. Working on himself, a man tears the hard crust of sin from his intellect, refines it and makes it capable of discernment. 

St Justin Popovich