The concept of encyclopedic knowledge was once attributed to exceptionally well-read or knowledgeable persons such as Plato, Aristotle, Hildegard von Bingen, Leonardo da Vinci, Immanuel Kant, or G.W.F. Hegel. Professor Tom Rockmore described Hegel, for example, as a polymath and "a modern Aristotle, perhaps the last person to know everything of value that was known during his lifetime." Such persons are generally described as such based on their deep cognitive grasp of multiple and diverse fields of inquiry—an intellectually exceptional subset of philosophers who might also be differentiated from the multi-talented, the genius, or the "Renaissance man."