When we build a house we do not put on the roof before laying the foundation–this is impossible. We first lay the foundations, then build the house, and finally put on the roof. We must do the same in relation to spiritual matters. First we must lay the spiritual foundations of the house, that is to say, we must watch over the heart and curtail the passions arising from it. Then we must build the walls of the spiritual house, that is to say, through the second form of attentiveness we must repulse the turbulence of the evil spirits that fight us by means of the external senses, and must free ourselves as quickly as possible from their attacks.
Then we must put on the roof, that is to say, detach ourselves entirely from all things and give ourselves wholly to God. In this way we complete our spiritual house in Christ Jesus our Lord, to whom be glory throughout all the ages. Amen.
~St Symeon the New Theologian