Cuneiform was the first known form of written language, but spoken language is believed to predate writing by tens of thousands of years at least. A language is a dynamic set of visual, auditory, or tactile symbols of communication and the elements used to manipulate them. Language can also refer to the use of such systems as a general phenomenon. Language is considered to be an exclusively human mode of communication; although other animals make use of quite sophisticated communicative systems, none of these are known to make use of all of the properties that linguists use to define language. In Western Philosophy, language has long been closely associated with reason, which is also a uniquely human way of using symbols. In Ancient Greek philosophical terminology, the same word, logos, was used as a term for both language or speech and reason, and the philosopher Thomas Hobbes used the English word "speech" so that it similarly could refer to reason, as will be discussed below. More commonly though, the English word "language", derived ultimately from lingua, Latin for tongue, typically refers only to expressions of reason which can be understood by other people, most obviously by speaking.