The NEXT line in the Catechism says this..
406 The Church's teaching on the transmission of original sin was articulated more precisely in the fifth century, especially under the impulse of St. Augustine's reflections against Pelagianism, and in the sixteenth century, in opposition to the Protestant Reformation. Pelagius held that man could, by the natural power of free will and without the necessary help of God's grace, lead a morally good life; he thus reduced the influence of Adam's fault to bad example. the first Protestant reformers, on the contrary, taught that original sin has radically perverted man and destroyed his freedom; they identified the sin inherited by each man with the tendency to evil (concupiscentia), which would be insurmountable. the Church pronounced on the meaning of the data of Revelation on original sin especially at the second Council of Orange (529)296 and at the Council of Trent (1546)
Here is a good historical article on this that shows what the Greek and Latin Fathers said.Blessed Augustine made some error's as well
http://www.catholicculture.org/library/view.cfm?recnum=7529
I wish you a Blessed evening!
Yes, and please note that it ends without a clear explanation. Pelagius believed that man could come to God without the help of God's grace. This is very similar to the Orthodox's view that man is capable of moving towards God.
But in the first Catechism that you've posted we saw man's inclination was towards sin. If man has this inclination towards sin, how is it possible for man to ever overcome it unless God gives man the power and ability to overcome it? And if God gives man the power and ability to overcome it, then won't they overcome? Thus the Reformers are more in keeping with this western doctrine.