Definition: In philosophy, transcendentalism is an idea that suggests that certain concepts or ideas are beyond human understanding and cannot be fully grasped by mere rational thought. This concept is often associated with the belief in non-physical substances, such as atoms and matter, which can exist independently of our perceptions. Transcendentalists believe that these concepts are "transcendent" because they transcend a particular set of physical laws or principles, like Newtonian mechanics, which can be understood by human reason.