What metaphors are used in Medieval Mystics by ?

Catherine of Siena, who in general is quite conventional in this regard, appears to have invented her own extended metaphor of Christ as a bridge. She writes in The Dialogue that this bridge stretches from heaven to earth and has three stairs, which correspond to three spiritual stages and to three parts of Christ's body. The first stair is the feet, which symbolize the qualities of the individual mind; the second, the heart, which is love; the third, the mouth, which symbolizes peace.