Background: Benjamin Lee Whorf (; April 24, 1897 - July 26, 1941) was an American linguist and fire prevention engineer. Whorf is widely known as an advocate for the idea that differences between the structures of different languages shape how their speakers perceive and conceptualize the world. This principle has frequently been called the "Sapir-Whorf hypothesis", after him and his mentor Edward Sapir, but Whorf called it the principle of linguistic relativity, because he saw the idea as having implications similar to Einstein's principle of physical relativity. Throughout his life Whorf was a chemical engineer by profession, but as a young man he took up an interest in linguistics.
Context: Until his return from Mexico in 1930 Whorf had been entirely an autodidact in linguistic theory and field methodology, yet he had already made a name for himself in Middle American linguistics. Whorf had met Sapir, the leading US linguist of the day, at professional conferences, and in 1931 Sapir came to Yale from the University of Chicago to take a position as Professor of Anthropology. Alfred Tozzer sent Sapir a copy of Whorf's paper on "Nahuatl tones and saltillo". Sapir replied stating that it "should by all means be published"; however, it was not until 1993 that it was prepared for publication by Lyle Campbell and Frances Karttunen.  Whorf took Sapir's first course at Yale on "American Indian Linguistics". He enrolled in a program of graduate studies, nominally working towards a PhD in linguistics, but he never actually attempted to obtain a degree, satisfying himself with participating in the intellectual community around Sapir. At Yale, Whorf joined the circle of Sapir's students that included such luminary linguists as Morris Swadesh, Mary Haas, Harry Hoijer, G. L. Trager and Charles F. Voegelin. Whorf took on a central role among Sapir's students and was well respected.  Sapir had a profound influence on Whorf's thinking. Sapir's earliest writings had espoused views of the relation between thought and language stemming from the Humboldtian tradition he acquired through Franz Boas, which regarded language as the historical embodiment of volksgeist, or ethnic world view. But Sapir had since become influenced by a current of logical positivism, such as that of Bertrand Russell and the early Ludwig Wittgenstein, particularly through Ogden and Richards' The Meaning of Meaning, from which he adopted the view that natural language potentially obscures, rather than facilitates, the mind to perceive and describe the world as it really is. In this view, proper perception could only be accomplished through formal logics. During his stay at Yale, Whorf acquired this current of thought partly from Sapir and partly through his own readings of Russell and Ogden and Richards. As Whorf became more influenced by positivist science he also distanced himself from some approaches to language and meaning that he saw as lacking in rigor and insight. One of these was Polish philosopher Alfred Korzybski's General semantics, which was espoused in the US by Stuart Chase. Chase admired Whorf's work and frequently sought out a reluctant Whorf, who considered Chase to be "utterly incompetent by training and background to handle such a subject." Ironically, Chase would later write the foreword for Carroll's collection of Whorf's writings.
Question: What year did he attend Yale?

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