The
noosphere (; sometimes
noösphere) is the sphere of human thought. The word derives from the
Greek νοῦς (
nous "
mind") and σφαῖρα (sphaira "
sphere"), in lexical analogy to "
atmosphere" and "
biosphere". It was introduced by
Pierre Teilhard de Chardin in 1922 in his
Cosmogenesis. Another possibility is the first use of the term by
Édouard Le Roy (1870–1954), who together with Teilhard was listening to lectures of
Vladimir Ivanovich Vernadsky at the
Sorbonne. In 1936 Vernadsky accepted the idea of the noosphere in a letter to Boris Leonidovich Lichkov (though he states that the concept derives from Le Roy). Citing the work of Teilhard's biographer, Rene Cuenot, Sampson and Pitt stated that although the concept was jointly developed by all three men (Vernadsky, LeRoy, and Teilhard), Teilhard believed that he actually invented the word: "I believe, so far as one can ever tell, that the word 'noosphere' was my invention: but it was he [Le Roy] who launched it."