We have to understand that The Zohar is intended for revealing our point in the heart, and not for fulfilling our regular senses or intellect that belong to this world. You open the book and fall into despair because you don’t understand or feel it; but what kind of sensation or understanding do you expect? The Zohar impacts you in a different way, not the way you think it would.
You have prepared a barrel or a bucket (egoistic desires) and expect them to be filled with what seems like spiritual fulfillment, while you actually desire egoistic fulfillment. The Zohar, however, gives you a different type of receiving vessel – one that’s bestowing, anti-egoistic, as well as the corresponding fulfillment – the pleasure of bestowal.
These are the normal phases that every person goes through, gradually revealing his Kli, his attitude and the fulfillment he should expect. As a result all the delusions eventually fade away and one reveals the right Kli which is ready for the right kind of fulfillment.