Materialism is a philosophy that physical matter is the fundamental truth and that everything, including thought and consciousness, can be explained through physical interactions of matter. It rejects the existence of non-physical or supernatural entities like God, souls, spirits or angels. Implications of materialism include atheism since it denies anything exists beyond the natural, physical world. Materialism also questions concepts of an afterlife, morality and dualistic views of human nature. It asserts that knowledge must be based on empirical evidence from the senses and science alone.