Yoga Sutras 2.6, 2.7

2.6:Drig darsana sakyor ekamata iva asmita, Egoism is the identification, as it were, of the power of the Seer (Purusha) with that of the instrument of seeing (body-mind).

Patanjali continues his definitions of the klesas. In my blog on sutras 2.2 and 2.3 I already touched on this subject. I believe that the concept of ego is a misunderstood concept. It is generally assumed that it is not good to have an ego or especially a big one. In western psychology to have an intact ego structure is a definition of sanity and conversely to not have an intact ego structure would mean insanity. In Yoga asmita, egoism or i-am-ness, or as I have used earlier, the sense of being separate, is the first outcome of ignorance. Ignorance, the lack of experiencing oneself as God, is the condition we have inherited as human beings, says Sri Patanjali. Therefore the removal of asmita involves realizing one's true nature as God. How to do this has been discussed throughout the yoga sutras already but will be broken down step by step as we explore this chapter on practice.

2.7: Sukha anusayi ragah, Attachment is that which follows identification with pleasurable experiences.

This sutra is confusing to some and I have heard interpretations saying that Patanjali is advocating denial of any type of pleasurable experience. Raga, which can be translated as attachment, attraction, desire or liking is the outcome of missing the inner fullfillment that comes with union with God or Pursha. This is why Patanjali says that the first klesa ignorance, is the cause of the other four klesas. Without this higher form of joy the human in his/her state of separation consciousness (egoism), clings to whatever joy that comes by. The more the unfullfilled person gets some pleasure out of the senses the more attached and therefore unhappy the person (when one doesn't have whatever pleasure that is) is. You can see how one could just say ice cream is bad because it makes you unhappy when you don't have it therefore one should never have ice cream. This approach works with some of the very destructive addictions such as heroine or alcohol but the real item needed is a little bit of bliss from inside. In one of my favorite passages from the Bible, Christ is talking at a well to a Samaritan woman, "...whosoever drinketh of this water shall thirst again: But whosoever drinketh of the water that I shall give him shall never thirst; (see John 4:7-14 for complete story) It is this inner spiritual joy that I believe he is talking about.
Without complete unity with Purusha one can't be completely balanced with pleasure. This is why later in the second limb of the eight limb path Patanjali tells us to be continent-to practice moderation.