Imperfections

"While venial sin always consists in a more or less slight transgression of one of God's laws, imperfection is the omission of some good act to which we are not obliged by any law, but which charity invites us to do.  To illustrate:  when I am aware of the possibility of performing a better act suited to my state, in accord with my actual capabilities, in harmony with my duties, and for the accomplishment of which I may reasonably believe that I am inspired by the Holy Spirit, I cannot deliberately refuse to do it without real actual imperfection.  In this case, my refusal to perform a better act cannot be judged to be good, not can it be justified by the thought that I am free to omit this better action since no law or commandment obliges me.  This would be an abuse of that liberty which was given me by God for the sole purpose of making me capable of adhering to the good, uninfluenced by my passions.  In fact, in the last analysis, my refusal to perform the better act always implies a lack of generosity, motivated by a little selfishness, laziness, meanness, or fondness for my own comfort, all of which are evidently contrary to perfection...

Every kind of imperfection in fact always comes from a want of effort, energy, and fervor in the spiritual life.  It is always selfishness which, in one way or another, takes something away from God to satisfy the ego.  We are too calculating, afraid of giving too much, and so selfishness clips our wings and keeps us from reaching full union with God."
  --Divine Intimacy, pp. 300-301