I think of "illusion" as a vision in the mind, a picture dream of what we desire the perceived object to be. For instance when we are young we are attracted to another who we perceive as "beautiful" or "handsome", because all we see is flawless youth. We want that youth to be permanent. When we fall in love the object of our desire is "perfect". We tend not to see what things will be or might be , but what we want them to be. It could be a table, or a new pet. This "illusion" leads to attachment, followed by jealousy, anger or greed. I am a beginner in the beginner's forum. And, I can't keep up with a lot of the expert's arguments, but I'll try.