The Chinese Zen Master Ching Ch'ing was famous for his strict discipline. Late one night as he sat with the monks he asked them, "What's that sound outside the gate?" One of the monks replied, "Master, that's the sound of raindrops." Ching Ch'ing then said, "This world is upside down; people lose themselves and chase after things."
If you look closely at our world it's apparent that something is very wrong. Everywhere you look there is suffering. Why? The Buddha said that the cause of suffering is desire: "I want... something." Anytime you want something you lose your true self and are "chasing" after that something. Suddenly the world flips over like an unbalanced iceberg... bluuuuuub! Once the world is upside down, everything is seen differently. The Buddha called that ignorance. And just like a fish in water, we don't realize our ignorance until the wake-up alarm of suffering starts ringing loudly in our ears. In fact, when we hear people talking about the right-side-up world, we tend to reject it immediately. "That's not true; no way, you must be crazy or some kind of religious nut!"
Ignorance doesn't include just our material desires, it can also embrace our "spiritual" practices as well; these too can become things. As Zen Master Huang Po, Lin Chi's teacher, said: "So, if you students of the Way are mistaken about your own real Mind... you will indulge in various achievements and practices and expect to attain realization by such graduated practices. But, even after aeons of diligent searching, you will not be able to attain to the Way. These methods cannot be compared to the sudden elimination of conceptual thought, the certain knowledge that there is nothing at all which has absolute existence, nothing on which to lay hold, nothing on which to rely, nothing in which to abide, nothing subjective or objective. It is by preventing the rise of conceptual thought that you will realize Bodhi; and, when you do, you will just be realizing the Buddha who has always existed in your own Mind."