This week in my homily I mentioned the book, The Four Cardinal Virtues, by Josef Pieper from which came the quote on pride which I used in my homily:
Pride is not, in the first place, a quality of everyday behavior in human relationships. Pride refers to man's relationship to God. Pride is the anti-realistic denial of the relationship between creature and Creator; pride denies the creaturely nature of man.
(Chapter on Humility, page 191)
The link to an e-version of this book can be found here. If you wish to purchase the book, it is available here. You may want to consider reading it as Spiritual Reading to increase your knowledge of the faith and to edify your soul.
I also had mentioned C.S. Lewis and his words regarding insights on why Pride is the greatest sin. This is also a very good read for a better understanding of the meaning of pride. The article with CS Lewis' words on pride can be found HERE.