Our senses have been turned outwards by design. We see things outside, we hear, smell, taste, touch and our attention flows continually outwards. So this turning away from the world for a while is very necessary for communion with God. However you might do, by the way of avenging yourself on a brother who has done you some injustice, we'll turn into a stumbling block for you at the time of prayer. The man who stores up injuries and resentments and yet prays might as well draw water from a well and pour it into a cask that is full of holes.