"The tongue is a small member, but it does big things. A religious who does not keep silence will never attain holiness; that is, she will never attain holiness; that is, she will never become a saint. Let her not delude herself - unless it is the Spirit of God who is speaking through her, for then she must not keep silent. But, in order to hear the voice of God, one has to have silence in one's soul and to keep silence; not a gloomy silence, but an interior silence; that is to say, recollection in God. Once can speak a great deal without breaking silence and, on the contrary, one can speak little and be constantly breaking silence. Oh, what irreparable damage is done by the breach of silence! We cause a lot of harm to our neighbor, but even more to our own selves.
"In my opinion, and according to my experience, the rule concerning silence should stand in the very first place. God does not give himself to a chattering soul, which, like a drone in a beehive, buzzes around but gathers no honey. A talkative soul is empty inside. It lacks both the essential virtues and intimacy with God. A deeper interior life, one of gentle peace and of that silence where the Lord dwells, is quite out of the question. A soul which has never tasted the sweetness of inner silence is a restless spirit which disturbs the silence of others. I have seen many souls in the depths of hell for not having kept their silence; they told me so themselves when I asked them what was the cause of their undoing. These were souls of religious. My God, what an agony it is to think that not only might have been in heaven, but they might even have become saints! O Jesus, have mercy!"
St. Faustina, Diary, 118.