You perceive the world with your five senses. When your mind perceives the world, then the world exists before you. But if we are born without any senses, then how could we perceive the world except as a dream in our minds? But then...dreams often seem as real as the world we see now. Look...If I touch you with this hand, I can remember touching you, but I can't ever prove I did. If reality is nothing more than what is in our mind, then what is the difference between this world and a dream?