The ignorant person images that oneself and dharmas (elements of our consciousness) really exist, whereas the wise person understands that all existence is dependent on other things (dependent co-arising) and not fundamentally real.
The Consciousness-Only School emphasizes a “three-fold” nature of existence:
(1) Only what can be imagined really exists,
(2) Everything is dependent on something for its existence, and
(3) All existence is ultimately empty in nature.