It seems to me that pride can come in two forms, both of which are dangerous to the spiritual life. Pride is defined as an inordinate love of self, or an inordinate desire for one's own perfection. Now, this inordinate love can manifest itself in these two forms:
The first and most striking form of pride is that in which the proud man possesses, or thinks he possesses, his desired goods, and as a result considers himself superior to all his fellow man. He refuses to admit that he has any faults, but considers himself the most excellent of men. He despises others when they do not meet to his standards of goodness, and is likely to treat them cruelly and contemptuously. He expects God to give him privileges and rewards which God cannot in fact give, and if he does not receive these privileges he can be led to rebellion and hatred against the Will of God, thinking he deserves such rewards when in fact he does not. Arrogance and presumption are the predominant vices in this manifestation of pride. This man loves his own perfection so much, that he will not even allow the thought to enter his mind that he lacks any of it.
The second form of pride is that in which the proud man does not possess the perfection he desires, and he recognizes this. When he strives to attain this perfection, but fails, he is driven to a state of utter despair and desperation. He fears his flaws to such an extent that can possibly render him deeply unappreciative of the mercy and forgiveness of God, and he constantly indulges in sentiments of sorrow and depression. Perhaps he begins to imagine that he has faults and defects which he does not in fact have, and very often feels shame where he should not feel it, or to a degree which exceeds the actual gravity of his flaws. His primary vices are scrupulosity and discouragement. He loves his own perfection too much, that when he fears he has not attained his perfection, he loses all hope.
Sometimes these forms manifest themselves as aspects of separate personalities - one person will tend toward the first kind, another towards the second - or they may be successive stages in the pride of a single person. Often it is the case that, first having indulged in presumptuous pride, a man's arrogance and presumption may wax, and discouragement and scrupulosity ensue, after the man has finally come around to recognizing his failure.
Persons who indulge in either kind of pride share one fatal flaw: they love and trust themselves more than they love and trust God. They do not recognize that it is the grace of God, not their own human efforts, which alone can lead them to perfection; or at least, they live as though they do not recognize it. God's grace is necessary to lead a good life, especially to lead a life of sanctity by which to come to eternal salvation. The belief that man can attain salvation by his own efforts without the grace of God amounts to the heresy of Pelagianism. Granted, there is a cooperation between God's grace and the efforts of man that is necessary for salvation; but part of this cooperation involves this very recognition of God's grace, the willing acceptance of the fact that we cannot be perfect without that grace.
In practice, this knowing and willing acceptance of grace amounts to an abandonment of self to Divine Providence. Abandonment to Divine Providence has two essential parts to it (I spoke a little bit about this Abandonment in this post): First, we must detach ourselves from worldly desires, from our self-will, from the desire of our own good and our own perfection. In the first place, this means we must, by an act of free will, rise above the influence of our emotions, and the desires connected to our emotions; eventually this will have the happy effect of subjecting the emotions to the influence of our will. Pride will be thus partially resolved here, insofar as we will now live as though our perfection and good were not dependent on our own efforts, for it is not; we will no longer have the inordinate urge to seek our own good. Second, we must seek to love nothing except that in which we see the Will of God. Our sole desire should be to directed by the Will of God. I believe St. Francis de Sales says something to the effect that the true lover of God would rather be in hell if God's Will was there, than in heaven if God's Will was not there. We must resolve that absolutely nothing can stop us from going along with God's Will. Thus again, pride will be resolved, and - more than this - humility attained, insofar as we will recognize that it is God's Will, God's providence, God's grace alone, by which we can become truly perfect.