From a letter of Saint Catherine of Siena to Blessed Raymond.
Most beloved father in our dear Christ Jesus. I Catherine, a minister and servant of the servants of Jesus Christ write you in his precious blood. I desire that you become a true spouse of the Truth himself, that you follow him and love him.
I see no way of tasting the truth and of living with it without self-knowledge. It is this knowledge that really makes us understand that we are not, and that our being came from God in whose image and likeness we were created. Through this knowledge we come to know that God created us a second time by giving us again the life of grace through the blood of the only Son, blood that had manifested to us the truth of God the Father. This is the divine truth: we were created for the glory and praise of God's name and to participate in the eternal beauty of God and so be sanctified in God. And what is the proof that this is true? It is the blood of the spotless Lamb.
How do we come to know this blood? By self-knowledge. We were that earth where the standard of the cross was planted. We were the vessel that received the blood of the Lamb flowing from the cross. Why were we this earth? Because the earth itself did not suffice to keep the cross standing erect; it would have refused such a great injustice. The nails would not have been enough to hold him fixed and nailed if his ineffable love of our salvation had not held him.
It was the flaming love for the glory of his Father and of our salvation that kept him on the cross. We are, then, that earth which supported the cross and the vessel that received his blood.
The one who has the knowledge of this Truth and who becomes its spouse will find in the blood all the richness and life of grace. The nakedness of such a person will be covered by the bridal gown and will be clothed by the fire of charity, for the blood and the fire meld and penetrate one another and it was love that united the blood to the divinity and that poured it out.
In the blood we are nourished and fed by mercy; in the blood we can dispel the darkness and enjoy light; for in the blood we can destroy the fog of self-love and overcome a servile fear of the One who punishes. Whoever does not love truth will not find truth in self-knowledge and the blood.
For this reason it is necessary for you to be the spouse of Truth, if you are to know Truth. Where will you do this? In the house of self-knowledge where you know that everything you have comes from God through a gratuitous grace; where you experience that re-creation which Truth bestows. This is what is means to be re-created in grace by the blood of the Lamb, to wash oneself, to submerge and kill the will. By any other way you will an unfaithful spouse of the Truth, rather than a faithful spouse. I said that I wanted to see you a true spouse of the Truth, because I desire this.