Ambrosiaster : Paul is saying this because if a Christian must boast, he should boast in humility, from which comes growth in God's sight. — COMMENTARY ON PAUL'S EPISTLES John Chrysostom : "If I must needs glory, I will glory of the things which concern my weakness." Seest thou that he no where glorieth of miracles, but of his persecutions and his trials? For this is meant by "weaknesses." And he shows that his warfare was of a diversified character. For both the Jews warred upon him, and the Gentiles stood against him, and the false brethren fought with him, and brethren caused him sorrow, through their weakness and by taking offense:-on every side he found trouble and disturbance, from friends and from strangers. This is the especial mark of an Apostle, by these things is the Gospel woven. — Homily 25 on 2 Corinthians