In the last century, Napoleon's armies opened a prison that the Spanish Inquisition had used. They found the remains of a prisoner who had been incarcerated for his faith. The dungeon was underground. The body had long since decayed. Only a chain fastened around an ankle bone cried out his confinement. But this prisoner, long since dead, had left a witness. On the wall of his small, dismal cell this faithful soldier of Christ had scratched a rough cross with 4 words surrounding it in Spanish. Above the cross was the Spanish word for "height". Below it was the word for "depth." To the left the word "width." To the right, the word "length." Clearly this prisoner wanted to testify to the surpassing greatness of the love of Christ, perceived even in his suffering.
As John Stott says in this passage, "The love of Christ is broad enough to encompass all mankind (especially Jew and Gentiles, the theme of these chapters), long enough to last for eternity, deep enough to reach the most degraded sinner, and high enough to exalt him to heaven."
James Montgomery Boyce. Ephesians: An Expositional Commentary. Baker Book House. Grand Rapids, Michigan. 1997. Page 111.