“For Jesus Christ is one man, having a Head and a body”
Source: On the Mystical Body of Christ, pp. 424-425
Context: What does the Scripture mean when it tells us of the body of one man so extended in space that all can kill him? We must understand these words of ourselves, of our Church, or the body of Christ. For Jesus Christ is one man, having a Head and a body. The Saviour of the body and the members of the body are two in one flesh, and in one voice, and in one passion, and, when iniquity shall have passed away, in one repose.
And so the passion of Christ is not in Christ alone; and yet the passion of Christ is in Christ alone. For if in Christ you consider both the Head and the body, the Christ’s passion is in Christ alone; but if by Christ you mean only the Head, then Christ’s passion is not in Christ alone. Hence if you are in the members of Christ, all you who hear me, and even you who hear me not (though you do hear, if you are united with the members of Christ), whatever you suffer at the hands of those who are no among the members of Christ, was lacking to the sufferings of Christ. It is added precisely because it was lacking. You fill up the measure; you do not cause it to overflow. You will suffer just so much as must be added of your sufferings to the complete passion of Christ, who suffered as our Head and who continues to suffer in His members, that is, in us. Into this common treasury each pays what he owes, and according to each one’s ability we all contribute our share of suffering. The full measure of the Passion will not be attained until the end of the world.