On How the House of the Soul is Built:

And I will tell you how to do it: First he must lay the foundation, which is faith. Without faith, as the Apostle says, it is impossible to please God. So according to our comparrison, it is impossible to build our (spiritual) house without this foundation (viz. faith). Is there occassion for obedience? A stone must be laid, obedience. Does a disagreement arise among the brethren? The stone of patience must be laid. Is there need for self-control? That stone too must be laid. So whatever the virtue required, that stone must be laid in the building, and in this way the perimeter of the building rises up. One stone for forebearance, another for mortifying self-will, one for meekness, and so on. In all this, great attention must be paid to perseverance and courage: these are the cornerstones of the building and by them the house is held together and all is united to all so that they do not lean over and fall apart; without these a man will not succeed on perfecting any of the virtues. If a man has no courage in his soul, he will not endure with patience, and if he has no patience he cannot entirely succeed. Therefore, it is said, "In your patience you shall possess your souls." Similarly, the building must set his stones in mortar. If he piles up his stones without mortar the stones come apart and the house falls down. The mortar is humility, which is composed from the earth and lies under the feet of all, as it says in the sayings of the Elders: "As it is impossible to contruct a ship without nails, so there is no hope in being saved without humility." Whatever a good man does, he must do with humility so that what he does is kept safe. But besides all this, the house needs what are called tie-beams or braces - that is to say discreation - which, besides adding much to its appearance, draws the whole building together.

St. Dorotheos of Gaza, On building up Virtues