Who should not commune?

“To be sure, it is true that those who despise it and live in an unchristian manner receive it to their hurt and damnation; for nothing shall be good or wholesome to them, just as with a sick person who from caprice eats and drinks what is forbidden him by the physician. But those who are sensible of their weakness, desire to be rid of it and long for help, should regard and use it only as a precious antidote against the poison which they have in them. For here in the Sacrament you are to receive from the lips of Christ forgiveness of sin, which contains and brings with it the grace of God and the Spirit with all His gifts, protection, shelter, and power against death and the devil and all misfortune.”