Today this theory is considered the first formulation of subjective idealism, a branch of idealism and a form of phenomenalism. Since it is not falsifiable, it is a theory not of science but of metaphysics and other philosophical methods. The idea that objects exist independently of mind is not testable or provable by the scientific method, because all objects we would wish to examine must enter our awareness in order to experiment on them. Nonetheless, a number of well established scientific experiments & principles (eg. Uncertainty principle, EPR experiment, Wheeler's delayed choice experiment) imply or suggest that the notion of a material reality, wholly apart from any awareness of it, may be untenable.
Earlier ideas about the immaterial and the incorporeal go back to Plato, Augustine, Plotinus, and many other ancient and medieval philosophers. Plato and Socrates made many references to eternal forms that are immaterial or incorporeal. A classic philosophical problem is whether or not there is a First Cause or Prime Mover prior to the material universe. Aristotle's notion of a formal cause is also partially related to Plato's idea of eternal Forms. Plato's theory of the divided line also mentions the intelligible method and the dialectical method that may lead one to The Good, or to what truly exists eternally, without change. The Good, unlike changing physical bodies, is claimed to exist in some incorporeal or immaterial state. Many philosophers have contrasted the notions of being and becoming in a similar kind of way.
Christian theology also refers to the incorporeal and immaterial in reference to God, the Holy Spirit, angels, and demons. This is in contrast to the corporeal human body of the physical realm that decays over time. The incorporeal is unchanging, whereas the corporeal is ever changing. Jesus was resurrected in a mysterious way that suggests some kind of incorporeal soul that can exist independently of the physical body. The ghostly appearance of various saints, prophets, and other supernatural beings imply some kind of immaterial realm. Some supernatural miracles can also imply the existence of the immaterial realm.
Bishop Berkeley's assessment of immaterialism was criticized by Samuel Johnson, as recorded by James Boswell. Responding to the theory, Dr. Johnson exclaimed "I refute it thus!" while kicking his shoe into a rock. This episode is cited by Stephen Dedalus in James Joyce's "Ulysses," chapter three. Reflecting on the "ineluctable modality of the visible," Dedalus conjures the image of Johnson's refutation, before engaging in his own refutation - closing his eyes and feeling the rocks under his feet while walking along the beach.