it's true because it's beautiful.

"For, as death came upon the human race by the disobedience of man, it was fitting that by man's [i.e., Christ's] obedience life should be restored.  And, as sin, the cause of our condemnation, had its origin from a woman, so ought the author of our righteousness and salvation be born of a woman.  And so also was it proper that the devil, who, being man's tempter, had conquered him by eating of the tree, should be vanquished by man in the suffering of the tree which man bore."

St. Anselm, Cur Deus Homo, Ch. III.