Immaterialism (also known as idealism) is a belief that all the things we experience—including our thoughts, feelings and consciousness—are not made up of physical objects, but rather exist only in our minds. Immaterialism says that the physical world is just an idea in our heads, and not something that we can actually touch or feel. This means that instead of physical objects like tables, chairs and rocks, the world is instead made up of mental or spiritual ideas. So, immaterialism suggests that we can only experience what is inside our minds and not the physical world outside.