A phenomenon (Greek: , phainomenon, from the verb phainein, to show, shine, appear, to be manifest or manifest itself, plural phenomena) is any thing which manifests itself. Phenomena are often, but not always, understood as "things that appear" or "experiences" for a sentient being, or in principle may be so. The term came into its modern philosophical usage through Immanuel Kant, who contrasted it with the noumenon. In contrast to a phenomenon, a noumenon is not directly accessible to observation. Kant was heavily influenced by Gottfried Wilhelm Leibniz in this part of his philosophy, in which phenomenon and noumenon serve as interrelated technical terms. In modern philosophical use, the term 'phenomena' has come to mean 'what is experienced is the basis of reality'. In Immanuel Kants Inaugural Dissertation, On the Form and Principles of the Sensible and Intelligible World (1770), Kant theorizes that the human mind is restricted to the logical world and thus can only interpret and understand occurrences according to their physical appearances. He wrote that humans could infer only as much as their senses allowed, but not experience the actual object itself. Thus, the term phenomenon refers to any incident deserving of inquiry and investigation, especially events that are particularly unusual or of distinctive importance. According to The Columbia Encyclopedia, "Modern philosophers have used 'phenomenon' to designate what is apprehended before judgment is applied." This may not be possible if observation is theory laden.